به انگلیسی

Rounding to a given accuracy

Mathematics · Number Representation & Place Value · ages 10-11

Name ______________________ Date ____________

Round 8.372 to 1 decimal place.
- 8.3
- 8.4
- 8.37
- 9.0
Round 3.72 to 1 decimal place.
- 3.7
- 3.8
- 3.72
If the digit right after the place you're rounding to is 5 or more, you round that place up.
Circle one: True False
You want to round 3.72 to 1 decimal place. Which digit do you look at to decide?
- The digit in the place you're rounding to, which is the 7
- The digit right after the place you're rounding to
- The first digit of the number, which is the 3 in the ones place
Estimate 7.6 times 2.2 by rounding each number first.
Answer: ______________
Round 4,249,999 to the nearest 100,000.
Answer: ______________
Round 6.284 to 2 decimal places.
Answer: ______________
Estimate 19.8 x 21 by rounding both numbers.
- About 400
- About 40
- About 300
- About 500
Josh rounds 3.748 to 1 decimal place and writes 3.8. What should he have done?
- He rounded correctly, because the 4 after the 7 tells you to round 3.748 up to 3.8
- He should have looked at the ones digit, 3, instead of the hundredths digit next to the 7
- He should have checked the hundredths digit, 4, which is below 5, so the answer is 3.7
Zara rounds 4,382,915 to the nearest 100,000 and writes 4,300,000. What mistake did she make?
- She rounded down, but the next digit is 8, so the answer should be 4,400,000
- She looked at the wrong place and rounded to the nearest 10,000 instead of 100,000
- She made no mistake, because 4,382,915 rounds down to 4,300,000 at the nearest 100,000

Answer key

For grown-ups. Fold this page away before handing over the rest.

8.4 · To round 8.372 to one decimal place, keep 8.3 and check the hundredths digit, 7. Since 7 is 5 or more, the answer is 8.4.
3.7 · The digit after the tenths place is 2, which is less than 5, so the tenths digit stays the same: 3.7.
True · When the next digit is 5 or more, you always round up.
The digit right after the place you're rounding to · Only the digit right after the place you're rounding to tells you whether to round up or leave it alone.
16 · 7.6 rounds to 8 and 2.2 rounds to 2. The estimate is 8 times 2, or 16.
4200000 · Keep the hundred-thousands digit 2 and check the ten-thousands digit 4. Since 4 is below 5, the result is 4,200,000.
6.28 · Keep 6.28 and check the thousandths digit, 4. Since 4 is below 5, the answer is 6.28.
About 400 · 19.8 rounds to 20 and 21 rounds to 20: 20 x 20 = 400.
He should have checked the hundredths digit, 4, which is below 5, so the answer is 3.7 · The digit after the tenths place is 4, which is less than 5, so the tenths digit stays at 7. The correct answer is 3.7.
She rounded down, but the next digit is 8, so the answer should be 4,400,000 · The digit right after the hundred-thousands place is 8, so it should round up, not down. The correct answer is 4,400,000.