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If the sum of digits of a number add to a multiple of 9, then the original number must be a multiple of 9.
You can multiply by nine on you fingers if the number is less than 10. Just hold up all your fingers (and thumbs) and put down the finger the represents the number you are multiplying. Lets say we want to multiply 7 by 9. Just put down finger 7. You will have 6 fingers to the left of finger 7 and 3 on the right, giving you 63. Or use 9. Put down finger 9, and you have 8 to the left and 1 to the right. Yes, 9 times 9 is 81.
The rule given at the top is why the finger trick works. You have 10 fingers, and if you put one down, you have nine. When multiplying any number between 1-10 by nine, adding the the digits of the product always gives nine - the same number as there are fingers left.
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What is 3 multiply 9?
3 multiply 9 = 27
What can you multiply to 5 to get 9?
The answer to the question of what can you multiply to 5 to get 9 is 4.
How do you turn Celsius into Fahrenheit?
-- take the Fahrenheit temperature -- subtract 32 from it -- multiply the result by 0.55 -- the result is the Celsius temperature This is another way. subtract 32 from the Fahrenheit temperature multiply by 5 divide by 9 (its just another way(i dunno if its faster or not XD))
What is 8 over 9 times 45?
The answer is 40. When you multiply 8/9 by 45, you first multiply the numerators (8 * 45 = 360) and then multiply the denominators (9 * 1 = 9). The answer is then 360/9, which simplifies to 40.
What two numbers multiply to get 9 and add to get 14?
23
