Question

Estimating Sums of Single Digit Numbers

Which of the following represents the most accurate estimation of 4 + 8? is the answer 5, 10, 20 or 25

Answer 1

10
We can round 4 down to 0 since it is less than 5 and round 8 up to 10 since it is greater than 5. Giving:
0 + 10 = 10