Mathematical trick: multiply by powers of 2

Wednesday, January 13, 2010

Students who follow courses in electronics and systems know that it is essential to know the binary system and as a result quickly calculate the powers of 2 of a number. As repeatedly explained below, the lecture method, with a little 'training will make you fast in mental calculation.
To multiply a number by 2, 4, 8, 16, 32 or any other power of 2 is sufficient to double the product as many times as is necessary for instance if you want to multiply a number by 16 is sufficient to recall that 16 is the product of 4 x 4 or in another form:

16 = 2 x 2 x 2 x 2

Let's see some examples

Example 1

We make the product 18 x 16 in

18 x 2 = 36
36 x 2 = 72
72 x 2 = 144
144 x 2 = 288

Example 2

Execute the product of 27 x 8

27 x 2 = 54
54 x 2 = 108
108 x 2 = 216

Example 3

Execute the product of 63 x 8

63 x 2 = 126
126 x 2 = 252
252 x 2 = 504