Today, I would like to share some strategies on doing multiplication problem dealing with number 9 and 5, which I find it very easy and useful for children.
Use Finger for Nine
Number your ten fingers from 1 to 10.
To start multiplying, on your fingers (starting with your thumb) count the number you are multiplying by and hold down that finger.
The number of fingers before the finger held down is the first digit of the answer and the number of finger after the finger held down is the second digit of the answer.
For example,
If you want to multiply 9 and 4, hold down your forth finger. The number of finger before the forth finger is 3 and after that is 6. Therefore, the answer is 36.
NOW...
Can you do 8 x 9 using your finger?
...
...
...
Can you get 72?
Well done!
Use Clock for Five
Generally, this strategy implies the concept of minutes in clock that every number carries five minutes. For example, if the long indicator is at number 5, it means 25 minutes. Therefore, children can use a clock to do five multiplication.
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