Divisibility Rules

Question 1

2

Answer 1

The last digit is even (0,2,4,6,8)
Example
128 is divisible by 2

Question 2

3

Answer 2

The sum of the digits is divisible by 3
Example
381 = 3+8+1 = 12

Question 3

4

Answer 3

The last 2 digits are divisible by 4
Example
1312 is divisible by 4

Question 4

5

Answer 4

The last digit is 0 or 5
Example
10, 25 end in 0 or 5

Question 5

6

Answer 5

The number is divisible by both 2 and 3
Example
138 Even (Divisible by 2)
and 1+3+8=12 (12/3=4) (Divisible by 3)

Question 6

7

Answer 6

If you double the last digit and subtract it from the rest of the number and the answer is:0 or 7
Example
672 (double 2 =4, 67-4=63 and 63/7=9) YES

905 (double 5=10, 90-10=80, and 80/7=113/7) NO

Question 7

8

Answer 7

The last three digits are divisible by 8
Example
109816 = last 3 digits = 816 can be divided by 8 = YES

Question 8

9

Answer 8

The sum of the digits is divisible by 9
Example
1629 = 1+6+2+9 = 18, 18/9 = 2 YES

Question 9

10

Answer 9

The number ends in 0
Example
10, 50, 100

Question 10

11

Answer 10

If you sum every second digit and then subtract all other digits and the answer is: 0 or 11
Example
3729 (7+9) - (2+3) = 11 YES

Question 11

12

Answer 11

The number is divisible by both 3 and 4 Example
648 (6+4+8 = 18 = divisible by 3 =YES)
and
48 divisible by 4 = YES