Divisibility rules of numbers

1. Divisibility rule of 3: -A number whose sum of digits is divisible by 3, then the number will be divisible by 3.                                                                                                                     
Ex:- 123, the sum of digits=1+2+3=6, divisible by 3, then 123 is also divisible by 3.

2. Divisibility rule of 6: -A number is divisible by 2 and 3 both, then the number is also divisible by 6.
Ex-23142 is divisible by 2 and 3, so 23142 is also divisible by 6.
Note-6=2★3, HCF(2,3)=1.

3. Divisibility rule of 9: -A number whose sum of digits is divisible by 9, then the number will be divisible by 9.

Ex:-342, the sum of digits=3+4+2=9, Divisible by 9, then 342 is also divisible by 9.