Mathematics of Aircraft Disasters

Pic of a Qantas 717
Image Source: http://www.aviationwa.org.au

If you don’t think Mathematics is vitally important, then think again!

The following news article we saw on an Australian news website today. It is all about a mathematical mistake that made a passenger plane nearly “stall” and fall out of the sky. It was very lucky that the plane did not crash.

In 2010, Pilots flying a regional Australian Qantas aircraft carrying 97 passengers were warned the plane was in danger of dropping from the sky during two bungled landing attempts.

An incident report released on February 9th 2012, said the captain and co-pilot wrestled with shaking joysticks as they tried to land the pitching Boeing 717-200 at an airport in Kalgoorlie, en route from Perth, in October 2010.

The Australian Transport Safety Bureau report found the drama resulted from the captain entering the wrong data on the plane’s weight into the flight computers — an error unnoticed by the co-pilot.

The plane’s landing weight was being calculated at 9.4 tonnes LIGHTER than its actual weight. (9.4 tonnes is about the weight of nine motor cars, and so this represents a very serious error).

This meant the subsequent mathematical calculations performed by the in-flight computer made the plane approach the landing strip at the wrong speed and angle.

The botched calculations twice triggered the “stick shaker” which alerts pilots to an impending aerodynamic stall — when the plane is no longer stable and may fall mid-air.

The warning was triggered during the first attempted landing at an altitude of 335 metres and again during the second attempt at 106 metres.

On both occasions the pilots failed to identify the underlying error and assumed air turbulence was to blame.

Normal descents take place at a constant airspeed and constant angle of descent (3 degree final approach at most airports). The pilot controls the angle of descent by varying engine power and pitch angle (lowering the nose) to keep the airspeed constant. If the nose is too high for the chosen power the airspeed will decrease until eventually the aircraft stalls or loses lift. 

Landing is the most difficult part of a flight, and mathematical equations programmed into the flight computers are used to instruct the pilots on how to safely guide the plane to the airport runway. Based on continuous mathematical calculations using equations and measurements made by the plane’s instruments, these computers give emergency warnings when things are not going correctly. (This part of the plane is called the “Avionics”). 

Because the plane’s computer thought the plane was lighter than it actually was, it calculated an angle of descent and speed that were not powerful enough for the heavy plane. The plane’s avionics computer detected that the plane was not going fast enough to maintain lift under its wings, and was in danger of stalling. This would mean the plane was coming down way too fast, and was going to land short of the runway, so the pilots had to quickly abort the landing.

Investigators said a lack of standard cross-checking routines allowed the data error to go unnoticed. They also said the captain, although “well rested”, had struggled to manage his fatigue owing to numerous roster changes.

The plane was operated by Cobham Aviation Services but was flying under the banner of QantasLink.

Raw Information Source: http://news.ninemsn.com.au/national/8417234/qantas-pilots-warned-plane-may-fall-from-sky

Overloaded Concorde Take Off Crash

pic of plane and wreckage
Image Source: http://lh3.ggpht.com

Air France Flight 4590 was a Concorde flight operated by Air France which was scheduled to run from Charles de Gaulle International Airport near Paris, to John F. Kennedy International Airport in New York City.

On 25 July 2000, it crashed in Gonesse, France. All one hundred passengers and nine crew members on board the flight died. On the ground, four people were killed with one left injured.

This was Concorde’s only accident in 25 years of flying in which fatalities occurred.

Post-accident investigation revealed that the aircraft was exceeding the maximum weight for ambient temperature and other conditions, and up to one ton over maximum structural weight.

Also, as it left the gate, it was loaded such that the centre of gravity was excessively located towards the back of the plane.

Although the overloaded weight did not directly cause the crash, it is thought to be a contibuting factor. The weight and incorrect centre of gravity probably helped tilt the plane upwards at an angle too large which caused fatal “stalling”.

“Stalling” is when a big plane is pointing up or down at an angle where it stops getting lift from air flowing under its wings. The plane then tilts up and literally falls backwards out of the sky, or goes into an uncontrollable nose dive.

Read full details of the crash on Wikipedia by clicking the link below:

http://en.wikipedia.org/wiki/Air_France_Flight_4590

Here is a diagram showing how the crash happened.

Blogspot plane crash diagram
Image Source: http://4.bp.blogspot.com

The following four minute video describes the Concorde plane, one of the most beautiful passenger planes to ever operate, as well as the fatal Flight 4590 crash.

[youtube http://www.youtube.com/watch?v=0-een7na2GU]

Overloaded Runaway Train

Wrecked Train Crash Pic
Image Source: http://www.gordon-elias.com

It is important that the weight of freight trains is accurately known when planning their trips.

On May 12th, 1989 the San Bernardino train disaster occurred in San Bernardino, California.

An out of control Southern Pacific Railroad freight train derailed on Duffy Street on the very steep Cajon Pass, killing two crew members and two children, ages 7 and 9.

Eleven homes were severely damaged or completely destroyed in the accident.

Thirteen days later fuel leaking from a pipe line damaged in the accident ignited, killing another 2 people and causing further damage to homes.

The cause of the crash was found to be that the weight of the train had not been correctly calculated. As a result there were not enough engines with enough braking power hitched up to the train for its steep descent down to San Bernadino from the nearby mountains.

Information Source: http://crazycrashes.wordpress.com/train-wreck-historical-timeline-1950-to-2000/

The following video is a 45 minute National Geographic documentary on the San Bernadino disaster.

The first couple of minutes of the video summarise what happened.

[youtube http://www.youtube.com/watch?v=OhOByrKb6FY]

Conclusion

Even though we have computers to do all the complicated mathematics involved with large transport machines, these computers still need to be given accurate numerical input including total weight, and other relevant variables such as wind direction and speed as well as runway surface conditions.

So next time they weigh your suitcase at the Airport, be confident that all the cargo and fuel gets weighed and added up correctly and entered into the plane’s flight computer.

Don’t worry, it is extremely unlikely that things will go wrong. Statistically planes are by far the most safest form of travel on earth.

Various estimates we found on the web rate the chance of dying in a plane crash to be about 1 in 9 milllion.

Information we found on the web says that the American National Safety Council puts your one-year odds of dying in a car accident at about one in 6500.

This means it is about 1400 times safer to fly in a plane than travel in a car!

The odds of dying in a car accident on the way to the airport, greatly surpass the odds of ever dying in a plane crash! (Because the Mathematics says so).

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Posted in Math in the Real World, Mathematics of Aircraft | Tagged , , , , , , , , , , , | 5 Comments

Multiplying Integers

3 x 7 rows of soldiers
Image Source: http://wme.cs.kent.edu

Can you work out how many soldiers are in the photo ?

We can see they are standing “three deep” : there is a soldier in the front, one in the middle, and one at the back.

There are three rows of soldiers.

We can also see that there are seven soldiers when we look across the front row of the photo.

So in the soldiers photo we have the following situation:

Diagram of 3 lots of 7 by addition
Image Source: http://www.utdanacenter.org

We can add up the seven lots of three and obtain an answer of 21.

Or we can multiply and say that 3 x 7 = 21 or 7 x 3 = 21.

Multiplication involves adding up how many lots of something we have.

For example 2 x 3 means we have “two lots of 3”, or 3 + 3, which equals 6.

4 x 3 means we have “four lots of 3”, or 3 + 3 + 3 + 3 which is 12.

When we have big numbers to multiply like 12 x 3, then we have to add up the three twelve times like this:

3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3

to obtain an answer of 36.

In primary school we learn our multiplying tables and know that 12 x 3 = 36, 7 x 3 = 21, 2 x 3 = 6, and so on.

It is much quicker and easier to know the multiplication tables than to write out long addition sums and add them up.

Multiplying Using Negative Numbers

But what about negative numbers ?

If we have 2 x -3

then we have two lots of -3

which is -3 + -3

which equals -6.

4 x -3 = ?

is four lots of negative 3

= -3 + -3 + -3 + -3

= -12

But what about something like:

-2 x 3 = ?

We can think of the negative sign at the start of the sum as meaning “the opposite of”.

So for -2 x 3 we need to find the opposite of 2 x 3.

Opposite of 2 x 3

= opposite of 6

= -6

So -2 x 3 = -6

Now here is the hardest one to get our head around:

-2 x -3

= opposite of 2 x -3

= opposite of 2 lots of -3

= opposite of -3 + -3

= opposite of -6

= +6 but we usually leave the positive sign off normal numbers

= 6

That was a very long lot of working out!

Integer Multiplication Rules

All the thinking and working out of how many lots of, and opposites of, and opposites of opposites, can get quite challenging.

But thankfully, Mathematicians noticed a pattern that Integer multiplications always follow, which goes like this:

Longhand Multiplying Rules

These Integer Multiplication Rules can be summarised as follows.

Mult Rules summary

In the summary diagram above:

+ means a positive number and does not mean addition.

– means a negative number and does not mean subtraction.

the “x” means multiply, and does not stand for the algebra variable “x”.

Integer Multiplying Rules Song

Here is a great short soulful song all about Integer Multiplying Rules.

[youtube http://www.youtube.com/watch?v=UHIZUE5iW-c]

Love Hate Rules for Multiplying Integers

These rules came from the webpage: http://7math.wikispaces.com/Integers

and they are a helpful way of remembering the multiplying rules.

It is good (+) to love (+), and it is bad (-) to hate (-)!

If you love to love, that is good. (positive x positive = positive)

If you love to hate, that is bad. (positive x negative = negative)
If you hate to love, that is bad. (negative x positive = negative)
If you hate to hate, that is good. (negative x negative = positive)

Same Sign Positive “SSP” Rule

The previous Integer Rules diagram we had was as follows:

Int Mult Rules Two

This diagram can be summarised even further:

Notice that the following always happens in the above diagram when multiplying integers:

Positive x Positive = Positive Answer

Negative x Negative = Positive Answer

If we multiply two items that have the same sign, we always get a positive answer.

If the items are not the same sign we get a negative answer when multiplying.

This is summarised into the sentence:

When MULTIPLYING : Same Sign Positive, Different Signs Negative.

Some people like to remember this rule in terms of relationships:

Two people the same will get along okay, and have a Positive relationship.

Two people that are completely different will probably not get along and have a negative relationship.

Multiplying Integers Video

The following video shows some examples that use the “same Sign Positive” rule.
[youtube http://www.youtube.com/watch?v=D3jfoq5HtXc]

Multiplying Integers Using the Triangle Rule

Some people like to summarise the integer multiplying rules into a Triangle, and draw this triangle next to their working out for each multiplying question that they do.

The following video shows how to do this.

Note that Americans use a dot instead of a multiplying “X” sign.

Also note that the same rules for multiplying also work for dividing, which we will be covering in a later lesson.

[youtube http://www.youtube.com/watch?v=R3M5Ktv3sLc]

Summary of Multiplying Rules

We hope we have not confused everyone by supplying so many versions of the Integer Multiplying Rules.
Here at Passy World we like to use “SSP” : “Same Sign Positive, otherwise Negative”, because we find it quick and easy.

However, we recommend that you pick the Rule method which works best for you.

The “+ – – Triangle”, or the “Love Hate” rules work just as well as “SSP”.

Example 1 : 4 x -3

The question contains different signed numbers multiplied together,
so using the “SSP” rule the answer needs to be Negative.

Mult Q1

Example 2 : -2 x -5

Here we have the same signs, and so using “SSP” rule, the answer will be Positive.

Mult Q2

Example 3 : -7 x 3

Here we have different signs, and so using “SSP” rule, the answer will be Negative.

Mult Q3

Example 4 : 2 x 9

Here we have the same signs, (both numbers are positive), and so using “SSP” rule the answer will be Positive.

Mult Q4

Integer Warp Multiplying Integers Game

To play this game We need to know our multiplying rules which are:

– x – = a Positive answer (Same Sign = Positive answer)

and

+ x – = a Negative answer (Different signs = Negative answer)

Click on the image below, or the text link which follows, to play this game.

Integers Warp Multiply Game

http://www.arcademicskillbuilders.com/games/integer-warp/integer-warp.html

Related Items

Introduction to Integers
Arranging Integers in Order
Adding Integers Using Number Lines
Adding Integers Using Zero Pairs
Subtracting Integers
Dividing Integers
Integers Order of Operations
Directed Number Integers Games
Integers in the Real World
Integers in Drag Racing

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Posted in Directed Numbers, Integers | Tagged , , , , , , , , , , , | 9 Comments

Subtracting Integers

Pic from web of Aussie Money
Image Source: http://www.business-visas-australia.com

Subtracting integers is difficult. This is because it can be hard to understand how we can take away things that already have a minus sign in front of them.

For example, let’s say that your friend owes you five dollars. This means that your financial relationship with them is currently -5. Eg. You have 5 dollars less, because you lent five dollars to them.

When they pay back the five dollars, the 5 dollar debt can be removed like this:

-5 – -5 = 0 debt, which is actually the same as -5 + 5 = 0.

Eg. We take their -5 dollar debt and add the 5 dollars they just gave you and this creates a debt of zero dollars.

SUBTRACTING A NEGATIVE IS ALWAYS THE SAME AS ADDING A POSITIVE.

A subtraction sum is always easier to do when we turn it into an addition sum.
This is what we always do with subtraction questions that involve integers.

WE ALWAYS CHANGE SUBTRACTION INTO ADDING THE OPPOSITE.

This is called the “Adding the Opposite Method”.

Adding the Opposite Method

Add the Opp PPT slide

Integer Addition sums are much easier to do than Subtractions, so we always apply the “Add the Opposite” rule to turn every Subtraction question into an Addition sum.

Keep Flip Change “KFC” Rule

Adding the Opposite can be simplified into what is called the “KFC” Rule.

Int Sub PPT KFC Rule

Example 1

5 – 2 = ?

We know the answer is 3, but let’s prove that KFC works.

Keep the 5 as it is, eg. It stays as +5, which is the same as 5
Flip the Subtract into Add
Change the sign of the 2 so that it becomes -2

Our KFC addition sum is: 5 + -2 which on a number line works out as 3.

Example 2

-5 – 2 = ?

Applying KFC, the -5 stays, and the 2 changes its sign to become -2

The KFC sum is therefore

-5 + -2 which works out as an answer of -7 .

eg. Using the “Cancel Zero Pairs” adding method we have:

Sub Int PPT Ex 1

We set this sum out in our workbook like this:

-5 – 2 = ?
K F C
-5 + -2 = -7

Example 3

-5 – -2 = ?

Applying KFC,
the -2 changes its sign to become 2
and our addition sum is:

-5 + 2 = ?

We can work out the answer to this sum using the canceling zeroes method as follows:

Sub Ints PPT Exmple 2

So the answer to our original question is: -5 – -2 = -3.

We set this sum out in our workbook like this:

-5 – – 2 = ?
K F C
-5 + 2 = -3

Videos About the “KFC” Rule

The following video shows how to use the KFC Rule for Integer subtractions.

Click anywhere on the video image below to launch the video in a new window.

Fake of Schooltube Ints Vid Two

This next video follows on from the previous one and gives some more “KFC” examples.

Click anywhere on the video image below to launch the video in a new window.

Fake of Schooltube Ints Vid Three

Subtracting Integers Car Racing Game

This game starts off with us using the left and right arrow keys to drive our car in a race, and then after a little while we have to stop and do an Integer Subtraction question.

If we get the question right, we get bonus items like a rocket booster pack to fly our car for a while, until the next question comes.

Click on the image below, or the link which follows, to play this game.

Subtracting Integers Car Race Game

http://www.math-play.com/math-racing-subtracting-integers-game/math-racing-subtracting-integers-game.html

Subtracting Integers Fish Game

In this fun game we have to click the letter that is the correct answer, before the fish swims to this correct answer.

Click on the image below, or the link which follows, to play this game.

Subtracting Integers Fish Game

http://www.slidermath.com/integer/SlamnS.shtml

Subtracting Integers Speed Test

This is more of an online speed test than a game.

However, it will certainly improve your Integer Subtraction skills.

Click on the image below, or the link which follows, to play this game.

Once you get onto the the new window screen, scroll down to find the Test.

Sub Integers Speed Test

http://www.basic-mathematics.com/subtracting-integers-game.html

Subtracting Integers Online Quiz

This online test will check how well we know our Integer Subtracting.

Click on the image below, or the link which follows, to play this game.

Once you get onto the the new window screen, scroll down to find the Quiz.

Sub Integers Online Quiz

http://www.aaamath.com/sub65_x4.htm

Related Items

Introduction to Integers
Arranging Integers in Order
Adding Integers Using Number Lines
Adding Integers Using Zero Pairs
Multiplying Integers
Dividing Integers
Integers Order of Operations
Directed Number Integers Games
Integers in the Real World
Integers in Drag Racing

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If you would like to submit an idea for an article, or be a guest writer on our blog, then please email us at the hotmail address shown in the right hand side bar of this page.

Enjoy,
Passy

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Posted in Directed Numbers, Integers | Tagged , , , , , , , | 6 Comments

Adding Integers Using Zero Pairs

Add Int Opening Pic 520 wide

Integers are all about Positives and Negatives.

Each passing day is full of Positive and Negative situations.

Diag 2

We can work out an overall score for our day by combining the negative scores with the positive scores.

Diag 3

We then cancel out each individual positive, with an individual negative to obtain an overall score.

Diag 4

Here is another example of cancelling out scores to obtain an overall value.

Diag 5

In this post we will show how to do adding Integers using the “Zero Pairs” Method.

This method involves cancelling out positive and negative pairs, and then seeing what is left over.

Adding Integers by Cancelling Zero Pairs

Example 1

Let’s first look at the example of +6 + -2

Diag 6

We have lined up each positive with a negative, and now we can cancel out to get our answer.

Diag 7

Example 2

-5 + 4 = ?

In this example we can see that there are five negatives, and four positives.

There are more negatives than positives, and so we should suspect that the answer should turn out to be a negative number.

Diag 8

We now group the zero pairs (eg. each group of -1 + 1 = 0), and determine the final result.

Diag 9

Example 3

-4 + -3 = ?

In this example there are no positives to form zero pairs with, and so the overall result should be negative.

Diag 10

Example 4

+3 + +2 = ?

In this example there are no negatives to form zero pairs with, and so the overall result should be positive.

Diag 11

Example 5

25 + -15 = ?

In this sum we have too many items to draw individually.

However, it should be fairly obvious that there are more positives (25 of them), compared to negatives (only 15 negatives).

Therefore the answer should be a positive number.

Diag 12

The final answer is the number of extra positives that we have left over at the end.

Diag 13

Passy World Video of Cancelling Zeroes Method

This You Tube Video gives a narrated version of PowerPoint slides which covers the same material as in this blog post about the Cancelling Zero Pairs method.

[youtube http://www.youtube.com/watch?v=omN_MvEhk0A&w=540&h=396]

You Tube Video About Zero Pairs Method

This You Tube Video is about Adding and Subtracting Integers using the Cancelling Zero Pairs method. It shows how to cancel out negatives with positives and then see what is left over to from the final answer.

[youtube http://www.youtube.com/watch?v=yteDWPyeNYI]

Blues Song About Zero Pairs Method

This You Tube blues song is about Adding and Subtracting Integers and uses the Cancelling Zero Pairs method. The quality is not very high resolution, and you may need to watch it a couple of times to get all the parts. It shows how to cancel out negatives with positives and then see what is left over to from the final answer.

[youtube http://www.youtube.com/watch?v=DS88fasSxKU&w=540&h=396]

Adding Integers Using Shortcut Rules

We can work out the sign of the final answer by identifying the larger amount of negatives or positives in the sum.

For 8 + -5, we have 8 positives, but only 5 negatives, and so the answer will be Positive.

When we cancel all of the five negatives with five of the positives, there are three positives left over.

The positives are in excess by 3, and so the answer is +3 or just 3.

For -10 + 3 we have more negatives than positives, and so the answer will be negative.

When we cancel all of the three positives with three of the negatives, there are seven negatives left over.

The negatives are in excess by 7, and so the answer is -7.

The following video shows these shortcut rules for adding Integers.

These rules are very useful for when we get experienced at adding directed numbers.

[youtube http://www.youtube.com/watch?v=R3ugqwQugVo]

Adding Integers Game – Spider Match

This is a fun game that helps us learn how to add Integers.

Click on a pair of numbered flies that add up to the required value in the center of the web and your spider should then eat them and give you a score. Keep clicking more pairs of numbers to get more points.

Click on the image below, or the text link which follows, to play this game.

Spider Match Game

http://www.arcademicskillbuilders.com/games/spider-match/spider-match.html

Related Items

Introduction to Integers
Arranging Integers in Order
Adding Integers Using Number Lines
Subtracting Integers
Multiplying Integers
Dividing Integers
Integers Order of Operations
Directed Number Integers Games
Integers in the Real World
Integers in Drag Racing

If you enjoyed this post, why not get a free subscription to our website.
You can then receive notifications of new pages directly to your email address.

Go to the subscribe area on the right hand sidebar, fill in your email address and then click the “Subscribe” button.

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How Free Subscription Works

If you would like to submit an idea for an article, or be a guest writer on our blog, then please email us at the hotmail address shown in the right hand side bar of this page.

Enjoy,
Passy

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Posted in Directed Numbers, Integers | Tagged , , , , , , , , | 8 Comments

Adding Integers Using Number Lines

Brazilian kids with number line
Image Source: http://1.bp.blogspot.com

Here are some students with a colorful Number Line they made. Number lines are a great way of learning to add Integers.

In Mathematics there are two ways of adding Integers.

The first method involves using a number line.

The second method involves cancelling out positive and negative pairs, and then seeing what is left over.

In this lesson we will look at adding Integers using a Number Line.

 
 

Adding Integers Using a Number Line

Many people like to use a number line for adding Integers, and this is a great method for beginners.

When doing an addition sum on the number line:

Negative numbers involve moving to the left, and positive numbers involve moving to the right.

We always start our sum at zero in the middle of the number line, and then move to locate the first number on the line.

If our second number is NEGATIVE, we move that many places to the LEFT.

If our second number is POSITIVE, we move that many places to the RIGHT.

The following You Tube video shows how to add integers by moving along a number line.

[youtube http://www.youtube.com/watch?v=ZxbXjORORSU]

 
 

Here is a longer You Tube video which shows several more examples of adding integers by moving along a number line.

[youtube http://www.youtube.com/watch?v=jostJyZ3KMI&w=420&h=315]

 
 

Adding Integers Example 1

In this example we are adding +3 and -5.

ALWAYS START AT ZERO

POSITIVE MEANS MOVE TO THE RIGHT

NEGATIVE MEANS MOVE TO THE LEFT

So we need to move starting from zero, 3 places to the right. We do this because our first number in the sum is +3.

Add Int Ex 1 pt 1

Next we move five places to the left, because our second number is -5.

Add Ints Ex 1 pt 2

We finish up at -2 on the number line, and this is our final answer.

Add Ints Ex 1 pt 3

Adding Integers Example 2

In this example we do the sum: +6 + -4

The completed sum of six to the right, then 4 left is shown below.

The resulting answer is +2 or just 2.

Add Ints Ex 2

 
 

Adding Integers Example 3

In this example we do the sum: -3 + -2

The completed sum of three to the left, then 2 more to the left is shown below.

The resulting answer is -5 .

Add Ints Ex 5

Adding Integers Example 4

In this example we are doing the sum: 0 + -2

Zero as the first number is neither positive or negative.

This means we start at zero as usual, and then we just stay at zero.

Next we move two positions to the left for the -2.

The resulting answer is -2.

This is shown in the number line diagram below.

Add Ints Ex6

Practice Number Line

Here is a Practice Number Line for doing Integer Addition Questions.

Practice Number Line

Integers Video

Here is a video about Integers and walking the number line that was made by some High School students.

[youtube http://www.youtube.com/watch?v=c9y_et9JyIM]

 
 

Here is another video which shows how to use a vertical “Elevator” Number Line.

Add Integers Using a Number Line from Amber Pasillas on Vimeo.

 
 

American Football Adding Integers Game

This is a fun game that helps us learn how to add Integers.

A loss of yards means a negative number, and a gain in yards means a positive number.

We click the mouse at the correct position on the number line to show the result of each world problem.

Click on the image below, or the link which follows, to play this game.

American Football Integers Game

http://www.mathgoodies.com/games/integer_game/football.html

 
 

Related Items

Introduction to Integers
Arranging Integers in Order
Adding Integers Using Zero Pairs
Subtracting Integers
Multiplying Integers
Dividing Integers
Integers Order of Operations
Directed Number Integers Games
Integers in the Real World
Integers in Drag Racing

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