PSAT Math : Arithmetic

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : Decimal Operations

At the store, green fabric costs $4.53 a yard. How much does 3.8 yards of green fabric cost? (Round to two decimal places.)

Possible Answers:

$17.21

$17.13

$17.31

$17.12

$17.22

Correct answer:

$17.21

Explanation:

This is a simple multiplication problem involving decimals. Simply multiply 4.53 by 3.8:

Now, round to the nearest two decimal places, giving an answer of 17.21.

Example Question #4 : How To Multiply Decimals

Find the product. Round to the nearest hundredths place.

Possible Answers:

Correct answer:

Explanation:

The hundredths place is the position two places to the right of the decimal. Our product is . Rounding to the hundredths place results in .

Example Question #1 : Decimal Operations

simplify: 0.2 ÷ 0.04

Possible Answers:
0.02
2
0.005
0.05
5
Correct answer: 5
Explanation:

0.2 ÷ 0.04  <- easiest way to approach is to move the decimal to the right (the same amount of spaces on each side) so that the decimal disappears

since 0.04 has 2 spaces and 0.2 only has 1, move the decimal 2 spaces to the right on each side

0.2 ÷ 0.04 = 20 ÷ 4 = 5

Example Question #1 : Decimal Operations

If the cost of 20 equally priced pencils cost $5.80, then at the same rate what is the greatest number of pencils you can purchase for $50?

Possible Answers:

173

150

172

172.41

200

Correct answer:

172

Explanation:

Remeber for this problem that you cannot spend more than $50. First find the price of each pencil by 5.80/20 = 29 cents. And then use this to do 50/0.29 = 172.41. So the greatest number of pencils you can purchase for $50 is 172 pencils.

Example Question #2 : Decimal Operations

Charlie has charges on his credit card of $63.70, $37.32, and $81.78. If he pays down half his bill at once, and then pays the rest in four equal monthly installments, how much is each monthly installment?

Possible Answers:

\$25.00

\$25.32

\$23.05

\$21.78

Correct answer:

Explanation:

Adding all the charges together and dividing by 2 yields $91.40. Dividing this by 4 yields a monthly installment of $22.85.

Example Question #3 : Decimal Operations

Simplify:

Possible Answers:

Correct answer:

Explanation:

Multiply both the numerator and denominator by some power of 10 to get rid of the decimals; in this case, multiply both by 10,000.

 

Example Question #501 : Arithmetic

Which number has 2.8 as its reciprocal?

Possible Answers:

Correct answer:

Explanation:

The number that has 2.8 as its reciprocal is, in return, the reciprocal of 2.8.

The reciprocal of this can be found by switching the numerator and the denominator. This is .

Example Question #6 : How To Divide Decimals

23 grams of sodium are equal to  atoms. How many atoms comprise one milligram of sodium?

(Select the closest answer)

Possible Answers:

Correct answer:

Explanation:

23 grams are equal to 23,000 milligrams, so to find the number of atoms in one milligram, divide:

Example Question #1 : How To Subtract Decimals

Round the answer to the nearest tenth.

 

Possible Answers:

Correct answer:

Explanation:

0.57 - 2.657 = -2.087

Don't forget the negative sign!

This number then rounds to -2.1.

Example Question #2 : How To Subtract Decimals

Simplify:

Possible Answers:

Correct answer:

Explanation:

Start by simplifying within the parentheses:

Then add/subtract each number

When you finish simplifying, the answer is 0.

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