Estimation involves approximating a quantity to an accuracy required. This is done by rounding off the numbers involved and getting a quick rough answer.

In other words, 3118 may be approximated to 3100 or to 3000, i.e. arriving at a value that is closest to the nearest hundred or to the nearest thousand depending on our need.

__Demonstration__:

** Question** 1. Estimate each of the following using the general rule:

(a) 530 + 998

(b) 796 – 314

(c) 12,904 + 2,888

(d) 28,292 – 21,496

__Answer__:

- 530 + 998

By rounding off to the nearest hundred, 530 rounds off to 500 and 998 rounds off to 1000. Estimated sum = 500 + 1000 = 1500

- 39,292 - 21,496

By rounding off to the nearest thousand, 39292 rounds off to 39000 and 21496 rounds off to 21000. Estimated difference= 39000 - 21000 = 18000