Rounding Large Numbers
Round any whole number up to 1,000,000 to the nearest 10, 100, 1,000, 10,000, or 100,000 using place-value understanding
What a learner can do afterwards
- Round 456,782 to the nearest 10,000 (460,000)
- Round 950,500 to the nearest 100,000 and explain the boundary case
- Use rounding to estimate the sum of 387,412 + 214,560
The lesson
You already know how to round numbers by checking one digit. Now you'll use that same trick on much bigger numbers, all the way up to a million. Find the place you're rounding to, then look at the digit right next to it.
Round 346,712 to the nearest 1,000, then to the nearest 10,000. For the nearest 1,000, check the hundreds digit: it's 7, so round up to 347,000. For the nearest 10,000, check the thousands digit: it's 6, so round up to 350,000.
You can also use rounding to check if an addition answer looks right. Estimate 387,412 + 214,560 by rounding each number to the nearest 10,000 first: 387,412 rounds to 390,000, and 214,560 rounds to 210,000. 390,000 + 210,000 = 600,000, close to the real total of 601,972.
Watch for the boundary case. Round 950,500 to the nearest 100,000: check the ten-thousands digit. It's 5, so you round up, even though the answer becomes 1,000,000, a whole new digit.
Find the place, check the digit right after it: 5 or more rounds up, anything less rounds down, and everything after becomes zero.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.