Neighbour numbers
Every number has neighbours, just like houses on a street.
- The number just before is one less.
- The number just after is one more.
- A number between two others sits in the middle.
For 15: the number before is 14, the number after is 16. So 15 is between 14 and 16.
Use a number line
10 — 11 — 12 — 13 — 14 — 15 — 16 — 17 — 18 — 19 — 20
- Before is one step left.
- After is one step right.
- Between is any number in the gap.
A quick table
| Before | Number | After |
|---|---|---|
| 6 | 7 | 8 |
| 19 | 20 | 21 |
| 29 | 30 | 31 |
| 99 | 100 | 101 |
Watch the tricky ones that cross a ten: before 30 is 29, and after 39 is 40.
More than one number between
Sometimes there are several numbers between two others. Between 4 and 9 are 5, 6, 7 and 8. To list them, count on from the first number and stop just before the second. The two end numbers themselves are not "between".
Worked examples
Example 1: What number is between 14 and 16?
Count: 14, 15, 16. Answer: 15.
Example 2: What comes just before 40?
One less than 40 is 39.
Example 3: List the numbers between 21 and 25.
22, 23, 24.
Common mistakes
- Mixing up "before" and "after". Before means count back; after means count on.
- Including the end numbers when listing numbers between.
- Decade changes: saying "twenty-ten" instead of 30.
Games to practise
- Neighbour cards: turn over a number card and say its before and after neighbours as fast as you can.
- Mystery number: a partner says "I’m thinking of a number between 30 and 32." You answer 31.
- Missing number train: write a row like 45, __, 47 and fill in the gap. Then try 58, 59, __.
- Hundred chart cover-up: cover one number on a hundred chart with a counter and work out what is hidden by looking at the numbers before and after it.
Try it yourself
- What comes just after 18?
- What comes just before 50?
- What number is between 7 and 9?
- List the numbers between 11 and 15.
Answers: 1) 19 2) 49 3) 8 4) 12, 13, 14
Quick recap
- Before = one less; after = one more.
- Between means the numbers in the middle, not the ends.
- A number line makes neighbours easy to see.