Tricks for Multiplying by 9
Question
To multiply any number by 9, write a zero after that number and then
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Hi, I'm Zoya Popova for About.com, and today I'm going to tell you about tricks for multiplying by 9. Learning the multiplication table can be hard, so having shortcuts is very helpful.When we multiply 9 by any single-digit number, our product will consist of two digits. The first digit will be that number minus 1. For 5x9, the first digit of the product will be 5-1=4. The second digit of the product will be 9 minus the first digit. So, for 5x9, the second digit will be 9-4=5. 5x9=45.For 9x9, the first digit will be 9-1=8; and the second digit will be 9-8=1:9x9=81. For 3x9, the first digit will be 3-1=2; the second digit will be 9-2=7:3x9=27.Another method that works for multiplying by 9 is very “hands on”. It uses your own fingers. Imagine your fingers are numbers from 1 to 10. To multiply any number by 9, hold down the finger that represents that number.For instance, to multiply 2 by 9, hold down your second finger. Now, count the fingers before and after it. We have 1 finger before our second finger and 8 left after it. So the answer will be 18. Let's say we're multiplying 5x9. Hold down your fifth finger. Now, we have 4 fingers before it and 5 fingers after it. The result is 45.And a final shortcut for multiplying by 9 goes like this. To multiply any number by 9, write a zero after that number and then subtract that number from the result. 6x9 is 60-6=54. In the same fashion, 4x9 will be 40-4=36.And those are the tricks for multiplying by 9.Thank you for watching, and for more information, please visit us at About.com.