Objective
At the end of this lesson, students should be able round decimal numbers to the nearest whole number, tenth, hundredth or thousandth.
Rounding a decimal means representing it by a number to which the decimal is nearest to.
Rounding a decimal numbers allows us to write the number in a way to suit our purposes. Decimals can be rounded to the nearest whole number, tenth, hundredth, thousandth, etc.
If we are to round to the nearest whole number:
a) 3.54 = 4 b) 3.49 = 3 c) 3.504 = 4 d) 3.497 = 3
A similar idea is what we use to round figures. Below are some examples:
Example 1
Round these decimal numbers to the nearest whole number.
a) 2.63 b) 13.429 c) 238.532
Example 2
Round to the nearest tenth (1 decimal place):
a) 4.829 b) 13.499 c) 6.952
Example 3
Round to the nearest hundredth (2 decimal places)
a) 4.826 b) 267.199 c) 10.841
Example 4
Round to the nearest thousandth (3d.p)
a) 2.8469 b) 18.2195 c) 9.1111
Solution
a) 2.8469 = 2.847
b) 18.2195 = 18.220
c) 9.1111 = 9.111