A composite number can be factored many different ways. For instance,
not including multiplication by one, can be factored in distinct ways:
Recall that the digital root of a number, in base , is found by adding together the
digits of that number, and repeating that process until a number is
arrived at that is less than .
Thus the digital root of is
.
We shall call a Digital Root Sum (DRS) the sum of the digital roots
of the individual factors of our number.
The chart below demonstrates all of the DRS values for .
Factorisation
Digital Root Sum
The maximum Digital Root Sum of is .
The function
gives the maximum Digital Root Sum of . So .