We are going to continue looking at using rounding in order to help us to work out addition calculations.
Let’s have a look at the following question.
63 + 80 =
How can we use rounding to help us to work out the answer?
We would round 63 to the nearest 10.
What is 63 to the nearest 10?
60
It is important to note that, we have subtracted 3 from 63 to get to 60.
Now, our question is 60 + 80.
If we worked out the answer to this, we would get 140.
Now, we need to revert the rounding we did earlier.
We subtracted 3 before, this means now we need to add 3.
140 + 3 = 143
So, 63 + 80 = 143
Your turn.
Use rounding to answer the following questions.
60 + 52
64 + 70
81 + 160
134 + 90
120 + 53