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Multiples of 9 (Method 1)

To multiply any number by 9, multiply the number by 10 and subtract the original number.

Examples:

9 x 1; (1 x 10) - 1 = 10 - 1 = 9

9 x 2; (2 x 10) - 2 = 20 - 2 = 18

9 x 3; (3 x 10) - 3 = 30 - 3 = 27

9 x 17; (17 x 10) - 17 = 170 - 17 = 153.

This works for every number.
Multiples of 9 (Method 2)


Rule 1 of Method 2:

When multiplying a number from 1 to 10 times 9, subtract 1 from the multiplier and write your answer down. Again subtract the answer written from the multiplicand 9 and write your second answer. Join the two answers to form your product.

Examples:

9 x 1; 1 - 1 = 0 and 9 - 0 = 9. Join 0 and 9 to form 09 or 9

9 x 2; 2 - 1 = 1 and 9 - 1 = 8. Join 1 and 8 to get 18 as your product.

9 x 3; 3 - 1 = 2 and 9 - 2 = 7. Join 2 and 7 to form 27 as your product.

9 x 8; 8 - 1 = 7 and 9 - 7 = 2. Join 7 and 2 to form 72 as your product.