Hello

is there a fast algorithm, similar to power of 2, which can be used with 3, i.e. n%3. Perhaps something that uses the fact that if sum of digits is divisible by three, then the number is also divisible.

This leads to a next question. What is the fast way to add digits in a number? I.e. 37 -> 3 +7 -> 10 I am looking for something that does not have conditionals as those tend to inhibit vectorization

thanks