Download Skills Workshop Estimating Fractions and Decimals

Skills Workshop
Estimating Fractions and Decimals
When estimating with fractions and decimals, you can use rounding skills to find numbers that are
easier to work with.
To round fractions, multiply the numerator by 2, and compare that number to the denominator. If
the multiplied numerator is less than the denominator, round down. If the multiplied numerator is
equal to the denominator or greater, round up.
EXAMPLE 1
Round each fraction to the nearest whole number.
2
9
a. 2
b.
5
16
SOLUTION
a. Multiply the numerator by 2:
2•2
4
= .
5
5
Because 4 < 5, the rounded number
is 2.
2
2 ≈2
5
b. Multiply the numerator by 2:
9 • 2 18
=
16
16
Because 18 > 16, the rounded
number is 1.
9
≈1
16
When rounding decimals, look at the digit to the right of the place being rounded. If the digit is
less than 5, round down. If the digit is 5 or greater, round up.
EXAMPLE 2
SOLUTION
Round each decimal to the place indicated.
a. 7.64; tenth
b. 3.467; hundredth
Look at the digit to the right of the place being rounded.
a. The digit 4 is to the right of
tenths place. Because 4 is less
than 5, round down.
So 7.64 rounds to 7.6.
b. The digit 7 is to the right of the
hundredths place. Because 7 is
greater than 5, round up.
So, 3.467 rounds to 3.47.
Round each fraction to the nearest whole number.
1. 5
2
9
2. 12
4
5
3. 16
3
7
4. 1
7
11
5.
12
19
Round each decimal to the place indicated.
6. 5.71; tenth
7. 6.406; hundredth
8. 83.45; tenth
© Cengage/South-Western
9. 18.7094; thousandth