Decimal Operations

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PSAT Math › Decimal Operations

Questions 1 - 10
1

simplify: 0.2 ÷ 0.04

5

0.005

0.05

2

0.02

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

2

simplify: 0.2 ÷ 0.04

5

0.005

0.05

2

0.02

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

3

Which of these decimals has the least value?

Explanation

Trailing zeros at the end of a decimal do not increase or decrease the value of a given decimal. However, zeros that appear after the decimal point and precede a non-zero number decrease the value of the number.

4

Find the sum.

Explanation

5

In the number 5,783.2935, what is the digit in the hundredths place?

\dpi{100} 9

\dpi{100} 5

\dpi{100} 7

\dpi{100} 8

\dpi{100} 3

Explanation

The digit in the hundredths place is the one two decimal places to the right of the decimal. That digit is 9. Do not confuse the hundredths with the hundreds place, which is three spaces to the left of the decimal.

The answer is 9.

6

Find the sum.

Explanation

7

In the number 5,783.2935, what is the digit in the hundredths place?

\dpi{100} 9

\dpi{100} 5

\dpi{100} 7

\dpi{100} 8

\dpi{100} 3

Explanation

The digit in the hundredths place is the one two decimal places to the right of the decimal. That digit is 9. Do not confuse the hundredths with the hundreds place, which is three spaces to the left of the decimal.

The answer is 9.

8

Which of these decimals has the least value?

Explanation

Trailing zeros at the end of a decimal do not increase or decrease the value of a given decimal. However, zeros that appear after the decimal point and precede a non-zero number decrease the value of the number.

9

can be represented by which of the following notations?

Explanation

In order to convert the decimal to scientific notation, count the number of spaces from the decimal point to the space between the 4 and the 6 (scientific notation requires that the leftmost number be a number between 1 and 10). In this instance it is 3 spaces. Since the decimal point will be moving from left to right, we know that our exponent will be negative, and in this case -3.

then becomes X .

10

If Johnny buys two comic books, priced at $1.50 each, and a candy bar, priced at $0.75, he'll have three quarters and two dimes left over. How much money does he have right now?

$4.70

$3.20

$5.10

$3.75

$4.35

Explanation

Add what he can purchase to what he has left over:

Two comic books and the candy bar: $1.50 + $1.0 + $0.75 = $3.75

Three quarters and two dimes: $0.75 + $0.20 = $0.95

Therefore his total amount of money is $3.75 + $0.95 = $4.70.

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