Neighbour numbers and round numbers
You learn to find the number just before and just after a number, and the round tens and hundreds.
How to work it out
- The neighbour before is 1 less: take 1 away.
- The neighbour after is 1 more: add 1.
- With tens and hundreds you look at the round number before and after.
A worked example
248
- Look at the number 248.
- Take away 1 to get the number before: 248 − 1 = 247.
- Add 1 to get the number after: 248 + 1 = 249.
- The neighbouring numbers are 247 and 249.
More examples
65
- Find the round ten just below 65: that is 60.
- Find the round ten just above 65: that is 70.
567
- Find the hundred just below 567: that is 500.
- Find the hundred just above 567: that is 600.
Try it yourself
Add 1 to the number
What number comes right after 29?
Find the round hundred just above
Which round hundred comes just after 734?
Watch out
When you look for the neighbours, you change the tens instead of the ones by mistake.
For the number before, take away exactly 1 from the ones. For the number after, add exactly 1.
Tips
- For the previous number you do − 1, for the next number you do + 1.
- Round tens always end in 0, and hundreds end in 00.
Why it works
Numbers stand in a fixed order. When you know which number comes before and after, you understand the number line better. That helps with quick counting and rounding.