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You can use the method Multiplying by 12 - 19 to multiply by 15 or you can use the following:
1. When multiplying n x 15, first divide n by 2.
2. Then add this number back to n and multiply by 10.
Ex [1] 15 x 32 =________.
a) 32 ÷ 2 = 16.
b) 16 + 32 = 48. 48 x 10 = 480.
c) The answer is 480.
Ex [2] 15 x 114 =________.
a) 114 ÷ 2 = 57.
b) 57 + 114 = 171. 171 x 10 = 1710.
c) The answer is 1710.
B. Please notice this method works only if n is even. If n is odd, I recommend using the method Multiplying by 12 - 19.
C. Some people believe that it is easier to use the Double and Half Method, but it depends on personal preference.