(1) making it possible to customize the rule. (3) The rules for divisibility by 2 and by 5—the two aforesaid exceptions— are based on the observation that, for p an arbitrary non-negative integer, 2 p (and, similarly, 5p ) divides N if it divides N mod 10 p , since 10p ...
The rule for divisibility by 7 is a bit complicated which can be understood by the steps given below: Example: Is 1073 divisible by 7? From the rule stated remove 3 from the number and double it, which becomes 6. Remaining number becomes 107, so 107-6 = 101. Repeating the process one...