Mental Math: Estimate Sums and Differences

Multiple Choice

When adding 45.472 and 36,768, which gives the more precise estimate: rounding the addends to the nearest ______.

• ten thousand

• thousand

• hundred

Open Ended

To which place would you round to estimate 6,904-4,111? Explain.

Open Ended

The diameter of Saturn is 120,536 kilometers. Its widest rings have a diameter 273,588 kilometers. To the nearest hundred thousand, about how much greater is the diameter of the rings than the diameter of Saturn?

Open Ended

Round to the nearest highest place value: 5,638 + 3,753.

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5,638 + 3,753

​6,000 + 4,000 = 10,000

Open Ended

Round to the nearest highest place value: 28,881 - 17,759.

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28,881 - 17,759

30,000 -20,000 = 10,000

Open Ended

Round to the nearest thousand: 63,526 + 25,038.

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63,526 + 25,038

64,000 - 25,000 = 39,000

Open Ended

Round to the nearest ten thousand: 262,262 -132,147

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262,262 -132,147

260,000 - 130,000 = 130,000