What is divisiblity rule for numbers 2to20?

Answer 1

In most cases, it is easier to do the division than to use some special divisibility rule. Divisibility rules only save you time in some special cases, such as:

• 2, 4, 8, 5, 10, 25 (look at the last digit or digits)
• 3, 9 (add the digits, and see if it is divisible by 3 or by 9, respectively)
• 7, 11, and 13 (separate the last three digits and subtract from the remaining number)