The Magic Number 6
The magic is - To multiply any number with 6, put that number in ones position, and number/2 in tens (or greater than tens) position. Basically, And this rule applies to both odd and even numbers. Let's start with simple examples with even number first: Example 1: 8 x 6 Here, N = 8, and N/2 = 4 8 x 6 = [N/2][N] = 48 For even numbers N >= 10: Example 2: 10 x 6 Here, N = 10 ( 1 is a forward carry) N/2 = 5 (+ carry) 10 x 6 = [N/2][N] = [5][10] = [5+1][0] = 60 Example 3: 28 x 6 Here, N = 28 ( 2 is a forward carry) N/2 = 14 (+ carry) 28 x 6 = [N/2][N] = [14][28] = [14+2][8] = 168 Example 4: 102 x 6 N = 102 ( 10 is a forward carry) N/2 = 51 (+ carry) 102 x 6 = [N/2][N] = [51][102] = [51 + 10][2] = 612 Example 5: 1234 x 6 N = 1234 ( 123 is a forward carry) N/2 = 1234/2 = 617 (+ carry) 1234 x 6 = [N/2][N] = [617][1234] = [617 + 123][4] = 7404 For odd numbers: Multiplication of 6 with odd number can be seen as a special ca