EstimatingTo the nearest ten
Name: Date:
Round each number to the nearest ten, then subtract.
1427 − 136
2427 − 411
3315 − 202
4315 − 158
5336 − 268
6434 − 323
7273 − 224
8322 − 224
Estimating differences worksheets
Estimating a difference means rounding both numbers first, then subtracting the friendly pair — 487 − 213 becomes 490 − 210, which is 280 and takes a moment. These free printable sheets keep to that one operation.
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Estimating differences
The answer key prints on a separate page.
What's on this sheet
Round first, then subtract — and the instruction says so, because the two orders do not agree. Rounding 487 − 213 gives 490 − 210 = 280, while subtracting first gives 274 → 270, and both are defensible. A printed sheet cannot hold two right answers, so it names the one it wants, which is also the one the standard means: an estimate is what you work out instead of the calculation, not a tidying-up afterwards.
Why this sheet works
The numbers are three digits, big enough that estimating earns its place. 8 − 3 rounds to 10 − 0, and a child who can take 3 from 8 has no reason to estimate anything; the exact answer here needs borrowing, so a quick 280 really is faster. Every number needs a decision too — none is already sitting on a ten — and the rounding never makes the two numbers equal, because 600 − 600 asks nothing at all.
How this one works
One question from this sheet, worked through a step at a time.
427 − 136
427−136
430−136
430−140
290
- Do not work it out exactly. Round each number first. 427 is nearer 430 than 420, so to the nearest ten it becomes 430.
- 136 is nearer 140 than 130, so to the nearest ten it becomes 140.
- Now it is easy enough to do in your head: 430 − 140 = 290.
- The exact answer is 291, so the estimate of 290 is 1 away. Close enough to catch a wrong answer with, and you did it in your head.