Divisibility rules

https://en.wikipedia.org/wiki/Divisibility_rule

"General" divisibility rule: to check divisibility by 10 in decimal numeral system, you only have to check if the last digit is 0. So, to check if d|n, express n in the base d, then check if the last digit is 0.

Divisibility rules in decimal system

• 1: always

• 2: LSD is even

• 3: digit sum is divisible by 3

• 10: LSD is 0

http://www.numberbases.com/divisibilitytest.html https://teresamccullough.wordpress.com/2011/05/25/divisibility-rules-for-numbers-in-bases-other-than-ten/ http://mathforum.org/library/drmath/view/72740.html https://math.stackexchange.com/questions/52778/divisibility-rules-and-congruences https://math.stackexchange.com/questions/148784/divisibility-rules-for-bases-other-than-10