Write an addition problem in which, when the addends are rounded to the nearest ten, the sum is 90. Then explain how you use estimation to solve the problem.
Sure! To create an addition problem where the sum is 90 when the addends are rounded to the nearest ten, we can use the following numbers: 48 and 42.
48 rounded to the nearest ten is 50.
42 rounded to the nearest ten is also 40.
If we add these rounded numbers, 50 + 40, we get 90.
Now, let's explain how we can use estimation to solve this problem. Estimation involves making a rough calculation to get a reasonable approximation of the answer.
To estimate the sum of 48 and 42, we can round each number to the nearest ten. 48 rounded to the nearest ten is 50, and 42 rounded to the nearest ten is 40.
Now, we can add these rounded numbers: 50 + 40 = 90.
By using estimation, we can quickly come up with a reasonable approximation of the sum without having to perform the exact calculations.