Multiplicative digital root
From Wikipedia, the free encyclopedia
The multiplicative digital root of a positive integer n is found by multiplying the digits of n together, then repeating this operation until only a single digit remains. This single digit number is called the multiplicative digital root of n.[1]
Multiplicative digital roots obviously depend upon the base in which n is written. If the term is used without qualification, it is assumed that n is written in base 10.
Multiplicative digitial roots are the multiplicative equivalent of digital roots.
[edit] Example
9876 would be reduced as 9876 -> 9x8x7x6 = 3024 -> 3x0x2x4 = 0. So the multiplicative digital root of 9876 is 0 and its multiplicative persistence (the number of steps required to reach a single digit) is 2.
