Hi Albert, wow that鈥檚 a lot of sweets. What鈥檚 Jerry doing?
Ah, labelling each jar with the number of sweets. But how do you now how many sweets each jar can hold?
Oh wow, impressive. With something like this you don鈥檛 need to be so exact.
You can round the number to give a rough estimate of how much the jar can hold instead鈥 lovely.
Rounding numbers gives a general idea of what the total is. It can make the number easier to understand, quicker to say, and in this case, leave a little wiggle room.
To round a number to the nearest ten, look at the ones.
Yep, that鈥檚 the one Jerry. If the number ends in five or more round it up. 156 is rounded up to 160.
But if it鈥檚 four or less, then round the numbers down.
To round a number to the nearest hundred, look at the tens digit and apply the same rule.
Five or higher, round up. Four or less, round down.
The same rules apply if we want to round to the nearest 1000. But instead, we look at the hundreds digit and round up or down from there.
Good idea Jerry, I think Albert鈥檚 had enough.
Rounding to the nearest 10
To round a number to the nearest 10, look at the units digit. If the units digit is 5 or more, round up. If the units digit is 4 or less, round down.
- The last digit in 356 is 6. So we round it up to 360.
- The last digit of 352 is 2. So we round it down to 350.
- 475 ends in a 5. We always round a 5 up. So 475 rounds up to 480.
Rounding to the nearest 100
To round a number to the nearest 100, look at the tens digit. If the tens digit is 5 or more, round up. If the tens digit is 4 or less, round down.
- The tens digit in 3281 is 8. So we round it up to 3300.
- The tens digit of 3216 is 1. So we round it down to 3200
Rounding to the nearest 1000
To round a number to the nearest 1000, look at the hundreds digit. If the hundreds digit is 5 or more, round up. If the hundreds digit is 4 or less, round down.
- The hundreds digit in 4559 is 5. So we round it up to 5000.
- The hundreds digit of 4295 is 2. So we round it down to 4000.
Quiz
More on Number and number processes
Find out more by working through a topic
- count21 of 25
- count22 of 25
- count23 of 25
- count24 of 25
