SAT Math : How to multiply decimals

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : Decimal Operations

45.728 x 3.2 = ?

Possible Answers:

14.63296

146329.6

1463.296

14632.96

146.3296

Correct answer:

146.3296

Explanation:

Multiply the numbers out in long format, then move the decimal point over the total number of decimal points in the two numbers (3 in the first, 1 in the second, so 4 total):

45.728 * 3.2 = 91456

91456 + 1371840 = 1,463,296 → 146.3296

Or just count the decimal points in the answer and make sure it's 4.

Example Question #35 : Other Decimals

At the farmer's market, oranges are $0.30 each, apples are $0.25 each, bananas are $0.40 each, and tomatoes are $0.60 each. If Scott buys 3 oranges, 7 apples, 4 bananas, and 8 tomatoes, how much does he spend?

Possible Answers:

$7.75

$10.40

$9.05

$11.40

$6.80

Correct answer:

$9.05

Explanation:

To find out how much Scott spends, we need to multiply the quantity of each fruit by its price and add them all up.

3 * $0.30 + 7 * $0.25 + 4 * $0.40 + 8 * $0.60 = $9.05

Example Question #11 : Decimals

If  is 25% of , what is the closest integer to the value of ?

Possible Answers:

Correct answer:

Explanation:

We can approximate the value of y pretty quickly:

y ≈ 1(0.50)(52) = 26

Since y = 0.25x = (1/4)x we know that x  = 4y ≈ 4(26) = 104

Example Question #3 : Decimal Operations

Possible Answers:

0.06

0.6

6

0.0006

0.006

Correct answer:

0.006

Explanation:

It's much easier to work with whole numbers, so we'll ignore the decimals for the first step: 5 x 12 = 60

Now look at the decimals. To add them back in, think of 60 as 60.0. Now move the decimal point four places to the left: 0.5 x 0.012 = .0060 = .006

 

Example Question #33 : Other Decimals

You bought a dozen eggs marked at  and received  change from . What is the percent of sales tax?  

Possible Answers:

Correct answer:

Explanation:

Set the equation up as 

 

Solve for , which equals  

or

Therefore the percent sales tax is: 

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