This week during Talking Maths, we are going to look at using rounding in order to help us to work out addition calculations.
Let’s have a look at the following question.
38 + 50 =
How can we use rounding to help us to work out the answer?
We would round 38 to the nearest 10.
What is 38 to the nearest 10?
40
It is important to note that, we have added 2 to 38 to get to 40.
Now, our question is 40 + 50.
If we worked out the answer to this, we would get 90.
Now, we need to revert the rounding we did earlier.
We added 2 before, this means now we need to subtracts 2.
90 - 2 = 88
So, 38 + 50 = 88
Your turn.
Use rounding to answer the following questions.
60 + 48
50 + 77
89 + 60
36 + 70
80 + 57