Check Answers by Rounding to the Nearest Ten

In this activity, we will be rounding 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.

49 + 62 = 111

Let's round the numbers to the nearest 10 to see if the answer is reasonable.

We round 49 up to 50  (the 9 rounds up)

We round 62 down to 60 (the 2 rounds down)

Now, let's add the rounded numbers:

50 + 60 = 110

Our rounded answer is a good estimate and shows us that 111 is a reasonable answer to the question.

If we had got an answer that was very different we would know that we had gone wrong!

Now, why don't you have a go at rounding some numbers to check if the answers are reasonable?

Good luck!