GRE Math : How to subtract negative numbers

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #1 : How To Subtract Negative Numbers

Quantity A:

Quantity B:

Possible Answers:

The relationship cannot be determined from the information given.

Quantity B is greater

Quantity A is greater

The two quantities are equal

Correct answer:

Quantity A is greater

Explanation:

Since both quantities have an , you can ignore this variable, which will give you  and for quantities A and B, respectively. Since  and  are both negative numbers,  must be bigger than , which means that no matter what numbers they are, Quantity A must be bigger.

Example Question #2 : How To Subtract Negative Numbers

If  and  are integers such that   and , what is the smallest possible value of ?

Possible Answers:

 

Correct answer:

 

Explanation:

To make  as small as possible, let  be as small as possible , and subtract the largest value of  possible :

Example Question #2 : Negative Numbers

Quantity A: 

Quantity B: 

Which of the following is true?

 

Possible Answers:

The two quantities are equal in size.

Quantity A is larger.

The relationship between the quantities cannot be determined.

Quantity B is larger.

Correct answer:

Quantity B is larger.

Explanation:

A problem like this one is very easy.  All you need to do is manage your arithmetic well.  Remember that when you subtract a negative number, this is the same as adding the positive of that number.  Therefore, you can rewrite each of your quantities:

Quantity A: 

Using a calculator, this comes out to be: 

Quantity B:

 

Using a calculator, this comes out to be: 

Therefore, quantity B is larger.

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