Time saving Divisibility Rules for numbers 1-9

Here are some simple rules of divisibility, which will help you in quick assumptions.

Divisibility by 2

- A number will be divisible by 2 if it's last digit is even

Divisibility by 3

- A number is divisible by 3, if SUM of its digits is MULTIPLE of 3

Divisibility by 4

- A number is divisible by 4, if it's Last TWO digits is divisible by 4

Divisibility by 5

-If it's last digit is 5 or 0

Divisibility by 6

- If both the divisibility rules of both 2 and 3 apply to a number then the number is divisible by 6 as well.

Divisibility by 7

- Take units place of the number and double it and then subtract it from the remaining number, then check if the resulting number is divisible by 7. if it does it is divisible else it's not .

This could be best understood by an example below.

Consider : 595
Unit's place is 5, so double it, i.e 10. Now subtract it from the remaining number (excluding unit's place no.) i.e 59
Now subtract 10 from 59,
59-10=49
49 is divisible by 7 ,so the number 595 is divisible by 7

Same is applied to even larger numbers say 45674
4567-8 = 4559
455 -18= 437
43-14 =29
29 is not divisible by 7, so the number 45674 is not divisible by 7


Divisibility by 8

- A number is divisible by 8 if it's last three digits are divisible by 8

Divisibility by 9

-A number is divisible by 9, If the SUM of it's digits if MULTIPLE of 9


Hope these little rules will help you some or the other way in your approach to a problem.


cheers!!