Question

What are the divisibility rules and how many are there?

Answer 1

Please read below.

Explanation:

Divisibility rules are rules, which enable one to identify whether a number is divisible by another smaller number or not, by examining digits and /or small operations on them but without attempting actual division or calculation.

There could be umpteen number of such rules, for example the divisibility rule of `125` could be that any number ending with `125,250,375,500,625,750,875` or `000` is divisible by `125`. The basis for such rules is generally modular arithmatic.

Most often used divisibility rules are , however, for numbers up to `10`, such as `2,3,4,5,6,7,8,9,10`, but have also been designed for numbers up to `20` and beyond. The latter are lot less frequently used.

If you need to find divisibility rules, you can just search socratic or web and you will find many, but one may not be comfortable with all types of divisibility rules.