Number Before and After

Idea

A whole number has a number immediately before it and a number immediately after it. These are the numbers that are 1 less and 1 more.

How to find them

1. Start with the given whole number.
2. To find the number before, subtract 1.
3. To find the number after, add 1.
4. Write the two answers in order: before, then after.

Example method

If the number is 8:

• Before: 8 − 1 = 7
• After: 8 + 1 = 9 So the numbers are 7 and 9.

Check your work

Make sure the before number is exactly one less than the given number, and the after number is exactly one more. On a number line, they should be the neighboring numbers on each side.

Tip

If the given number is 0, the number before is -1, but if you are working only with whole numbers, check whether negative numbers are allowed in the task.