In this worksheet children will learn about estimation by rounding numbers off to the nearest hundred or ten.
Example
Round these numbers off to the nearest hundred so that the answer can be estimated
321 + 689  can be rounded off to 

Estimated answer is C
Answer
A 321 rounds to 300 to the nearest hundred
B 689 rounds to 700 to the nearest hundred
C 300 + 700 = 1000