Before, after, and between, step by step
Knowing which number comes next is what turns counting into real number sense.
The question
? 8
?8
8− 1
78
- Counting forwards goes UP by one and backwards goes DOWN by one — so the only question is which way this gap is.
- The gap is BEFORE 8, so it is one less: 8 − 1.
- 8 − 1 = 7. Same ten, so only the last digit moves.
How it works.
- 01
Counting forwards goes UP by one and backwards goes DOWN by one — so the only question is which way this gap is.
- 02
The gap is BEFORE 8, so it is one less: 8 − 1.
- 03
8 − 1 = 7. Same ten, so only the last digit moves.