Thanks for the modulo function explanation regarding use of the remainder for determining the column location.
I find it easier to use the sum of the digits to find the location of each number with regards to column location, only because my brain is not comfortable with using division in my head, especially when I have only 30 seconds to decide what numbers to bet before the dealer says "No more bets."
Perhaps division is easier for others. So, it boils down to a matter of preference.