Why is it that whenever you multiply any number by nine the digits of the result always add up to a multiple of nine? Example:
9 * 7 = 63; // 6 + 3 = 9
9 * 35 = 315; // 3 + 1 + 5 = 9
Why is it that whenever you multiply any number by nine the digits of the result always add up to a multiple of nine? Example:
9 * 7 = 63; // 6 + 3 = 9
9 * 35 = 315; // 3 + 1 + 5 = 9