Divisibility Rules are important to check whether a number is divisible by any other number. This concept is used in many questions.
Divisibility Rule of 2
If the last digit or unit's place of the number is even, then the number is divisible by 2. Even means last digit is 0, 2, 4, 6 or 8.
Divisibility Rule of 3
Sum all the digits and check for the divisibility for the sum of the digits. You can repeat the procedure for big numbers.
Divisibility Rule of 4
Check the last two digits of the number. If the last two digits of the number are divisible by 4, then the number is also divisible by 4.
Divisibility Rule of 5
If the last digit of the number is 0 or 5, then the number is divisible by 5.
Divisibility Rule of 6
There is no separate rule for checking divisibility for 6. If the number is divisible by 2 and 3 both, then it will also be divisible by 6.
Divisibility Rule of 7
This one is little tricky. Subtract two times the last digit from the rest of the number. For example, if 3 digit number is xyz, then find (xy - 2z). If this number is divisible by 7, then the original number is also divisible by 7.
Divisibility Rule of 8
If the digit at the hundreds place (3rd digit from the right) is even, examine the number formed by the last two digits. If the hundreds digit is odd, examine the number obtained by the last two digits plus 4.
Divisibility Rule of 9
This is similar to divisibility rule of 3. Sum all the digits and check for the divisibility for the sum of the digits. You can repeat the procedure for big numbers.