In this Grade 4 enVision Mathematics lesson from Chapter 2, students learn how to estimate sums and differences of multi-digit whole numbers using rounding and place value. They practice rounding to the nearest thousand, hundred, and ten-thousand to find approximate answers, and use those estimates to check whether exact calculations are reasonable. Real-world contexts, such as library checkouts and ticket sales, help students apply estimation strategies to decide when an estimate is sufficient instead of an exact answer.
Section 1
Estimating Sums and Differences by Rounding
To estimate a sum or difference, first round each number to a specified place value, then perform the addition or subtraction on the rounded numbers. The result is an approximation, denoted by the symbol. For numbers and , an estimated sum is and an estimated difference is .
Section 2
Check: Using Estimation to Assess Reasonableness
To assess the reasonableness of a precise answer, compare it to an estimate made by rounding the numbers in the problem.
If the precise answer is close to the estimated answer, it is likely reasonable.
This can be represented as:
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Section 1
Estimating Sums and Differences by Rounding
To estimate a sum or difference, first round each number to a specified place value, then perform the addition or subtraction on the rounded numbers. The result is an approximation, denoted by the symbol. For numbers and , an estimated sum is and an estimated difference is .
Section 2
Check: Using Estimation to Assess Reasonableness
To assess the reasonableness of a precise answer, compare it to an estimate made by rounding the numbers in the problem.
If the precise answer is close to the estimated answer, it is likely reasonable.
This can be represented as:
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter