Rounding Off Numbers

“Rounding off” means making a number simple but keeping its value close to what it was. The result may be less accurate, but easier to use.

There are many ways to round. This is the most common method:

Worked Example 11.2.1:

i. Round 2345 to the nearest 10

ii. Round 1734 to the nearest 100.

iii. Round to the nearest thousand
(a) 14 514
(b) 3 453 16

i. 2345 to nearest  ten

Solution

5 unit is rounded up

The number in the tens increases by 1.

Hence 2  3  4 5  to nearest Ten is 2  3  5 0.

ii. Round 1734 to nearest Hundred.

Solution

3 is less than 5 so round down

Hence 1734 to the nearest hundred  = 1700.

iii. (a) 14 514 to nearest thousand.

Solution

TTH	TH	H	T	U
1	4	5	1	4

4 represents thousand here and the number next to it is 5 so we add 1 to 4

 Therefore, 14514    =   15000  to the nearest thousand.

iii. (b) 3453165 to nearest thousand.

M	HTH	TTH	TH	H	T	U
3	4	5	3	1	6	5

3 represents thousand here and the number next to it is 1 which is less than 1 so we round down

Therefore, 3 453165 = 3 453 000.