Question

Round each number to the nearest ten.

What is the best estimate for the answer to 552.17 – 48.35 ?

Answer 1

520 - 50 = ?

520 - 50 = 470

500 is the best estimate

Answer 2

So first round each number to the tens place so it would be;
550-50
And that would be 500 and so that's the best estimate. 
Hope this helps.