Unit 2 Decimal numbers
Rounding numbers
NOTE: rounded numbers are often used to estimate values or calculations
RULES: 1. Note place value desired
2. Note face value of digit to the right
a. if ≥ 5, then increase desired place value by 1
b. if < 5, then leave desired place value alone c. omit any digits to the right of the desired place value or replace them with 0 if desired place value is a whole number
Number
hundred
whole number
tenth
hundredth
4796.523
699.002
29.999
Remember place value for decimal numbers
0.542 68
5 ­ place value tenths
0.1 or 1/10 or 1/101 4 ­ place value hundredths
0.01 or 1/100 or 1/102 2 ­ place value thousandths
0.001 or 1/1000 or 1/103 6 ­ place value 10 thousandths 0.0001 or 1/10 000 or 1/104 8 place value 100 thousandths 0.000 01 or 1/100 000 or 1/105 Round to the nearest one, tenth and hundredth:
3.457
5.321
19.972
Assignment: worksheet ­ Rounding numbers
1