Lesson 3: Round Whole Numbers

Once students have a good understanding of place value, they are taught how to round numbers up to one million.

We use rounding to help us estimate our answers when adding, subtracting, multiplying, and dividing, to see if our answers are reasonable.

To estimate with addition or subtraction, you round both numbers to the highest place value position they both share, then add or subtract. Then, you check with the actual answer to see if your answer is reasonable.

To estimate with multiplication, you round the multi-digit number and multiply it by the single-digit number, or you round both multi-digit numbers and multiply them together. Then, you check with the actual answer to see if your answer is reasonable.