GRE Math : Decimal Operations

Study concepts, example questions & explanations for GRE Math

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Example Questions

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Example Question #1 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To add decimals, simply treat them like you would any other number.  Any time two of the digits in a particular place (i.e. tenths, hundredths, thousandths) add up to more than ten, you have to carry the one to the next greatest column.  Therefore:

So .

Example Question #351 : Arithmetic

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve this problem, subtract  from both sides of the eqution, 

Therefore, .

If you're having trouble subtracting the decimal, mutliply both numbers by  followed by a number of zeroes equal to the number of decimal places.  Then subtract, then divide both numbers by the number you multiplied them by. 

Example Question #3 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve, first add  to both sides of the equation:

Then add the decimals together:

Example Question #4 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve, you need to do some algebra:

Isolate x by adding the 4.150 to both sides of the equation.

Then add the decimals.  If you have trouble adding decimals, an effective method is to place one decimal over the other, and add the digits one at a time.  Remember to carry every time the digits in a given place add up to more than .

Example Question #5 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve for , first add  to both sides of the equation, so that you isolate the variable: 

Then, add your decimals, and remember that .

Example Question #6 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve, first add  to both sides of your equation, so you isolate the variable:

Then add the decimals together:

Example Question #1 : Decimals

Quantity A:

Quantity B:

 

Possible Answers:

Quantity A is greater.

The relationship cannot be determined.

The two quantities are equal.

Quantity B is greater.

Correct answer:

The relationship cannot be determined.

Explanation:

Use the values of .5 and 2 as possible x values. If x = 2, Quantity A is positive and greater, but if x = .5, Quantity A is negative and therefore smaller. As such, the relationship cannot be determined.

Example Question #11 : Decimals

Solve for :

Possible Answers:

Correct answer:

Explanation:

To solve for , subtract  from both sides of the equation.  , therefore, .

If you have trouble subtracting the decimals, you can multiply both of them by  to get whole numbers, then subtract as normal, then divide your result by 

Example Question #12 : Decimals

Possible Answers:

Correct answer:

Explanation:

Make sure to follow the order of operations. Begin by combining all terms inside the parentheses:

Convert the fraction to a decimal and once again complete the operations inside the parentheses:

The answer is .

Example Question #13 : Decimals

find 0.72

Possible Answers:

0.049

4.9

0.0049

0.49

49

Correct answer:

0.49

Explanation:

0.7 * 0.7 = 0.49

Trick: do the numbers without the decimals (7*7)

49; move the decimal of the answer the total number of spaces per each number (one for each 0.7)

0.49

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