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Counting backwards
Joyful Mathematics: Chapter 8
GoalCount back from any number up to 99.
New words
count back · say the numbers going downone less · the number beforesmaller · the numbers go down
Explanation
We can count back too. Going back means one less each time. Count back from 100: 100, 99, 98, 97. The numbers get smaller. On the number grid, go left to count back.
Worked examples
Count back from 60: 59, 58, 57.
| 85 | 84 | 83 | 82 | 81 |
One less than 70 is 69. Going back one step.
Class activity
Rocket count-down. Crouch low like a rocket. Count back from 20 to 10. At 10, jump up and say blast-off. Then try counting back from 30 to 20, and from 40 to 30.
Practice
1
Count back from 40 to 35. Say all the numbers.
40, 39, 38, 37, 36, 35.
2
What is one less than 70?
69
3
Fill the missing number: 75, 74, ?, 72.
| 75 | 74 | ? | 72 |
73
4
What is one less than 51?
50
5
Count back from 12 to 8. Say all the numbers.
12, 11, 10, 9, 8.