Answer:
- 1
- 40
- 36
Step-by-step explanation:
You know that 9 = 10 - 1.
Then 9 of something is equal to 10 of it less one of it. Here, that "something" is four.
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<em>Comment on this math</em>
This illustrates a shortcut for multiplying by 9 that can be convenient for mental arithmetic. The idea is to multiply by 10, which just involves adding 0 (or moving the decimal point), then subtract the original number.