Working with Large Numbers
Solve number and practical problems involving reading, writing, ordering, comparing, and rounding whole numbers up to 1,000,000
What a learner can do afterwards
- What is the largest six-digit number with digits summing to 15?
- A stadium holds 67,450 people. Round to the nearest thousand for a news report
- Order the populations of five cities and find the difference between the largest and smallest
1 · Read
You already know how to read big numbers and round them. Now you will compare numbers to see which is larger, and put a group of numbers in order from smallest to largest.
To compare two big numbers, first count the digits. A number with more digits is always bigger, no matter what those digits are. If the digit counts match, compare digit by digit starting from the left. The first spot where the digits differ decides which number is bigger.
To build the biggest six-digit number with digits that add to 15, put as much of that sum as you can into the leftmost digit. Try 9 first: that leaves 6 for the rest, so the next digit can be 6, and the last four digits become 0. The number is 960,000.
You already know how to round. Use that skill whenever a big number needs to sound simpler, like turning a stadium crowd of 67,450 into about 67,000 for a headline.
Count the digits first, then compare from the left until you find a difference: that tells you which large number wins.
More to read
1.2: Reading and Writing Whole Numbers
Big numbers can look scary, but they are just made of groups of three digits called periods. Starting from the right, the first group is the ones (ones, tens, hundreds). The next group is the thousands. The next group after that is the millions.
Commas separate each group, which makes big numbers easier to read. For example, 452,908 has two groups: 452 in the thousands and 908 in the ones. You would read it as "four hundred fifty-two thousand, nine hundred eight."
To write a number in words, read each group of three digits the same way you would read a small number, then add the group name (thousand, million) at the end of each group except the ones group.
To write a number from words back into digits, do the reverse. Figure out how many groups you need, then fill in each group's three digits, using zeros as placeholders for any empty spots.
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2 · Watch
به انگلیسیTake it off screen
Where it sits
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
16 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.