In this activity, we will round numbers to the nearest ten to estimate and check the answers to questions.
Rounding can help us see if the answer we have is reasonable.
Remember, when rounding to the nearest ten:
We round down if the ones are 1, 2, 3 or 4
We round up if the ones are 5, 6, 7, 8 or 9
Let's have a look at an example:
Remember to look at the ones column when deciding whether we need to round up or down.
567 + 612 = 1,179
Let's round the numbers to the nearest 10 to see if the answer is reasonable.
We round 567 up to 570 (the 7 rounds up)
We round 612 down to 610 (the 2 rounds down)
Now, let's add the rounded numbers:
570 + 610 = 1,180
Our rounded answer is a good estimate and shows us that 1,179 is a reasonable answer to the question.
Now, why don't you have a go at rounding some numbers to check if answers are reasonable?