Divisibility test of 13

Divisibility test of 13

 A number is divisible by 13 if the following is true:

 1. Multiply the ones digit by 4.

2. Add this value from the rest of the number.
3. Continue this pattern until you find a number you know is or is not divisible by 13.

Example        3159 is divisible by 13 because

a) 9 x 4 = 36.

b) 315  + 3 6 = 351
c) 1 x 4  = 4
d)  35 + 4 = 39  which is divisible by 13.

Example        22113 is divisible by 13 because

a) 3 x 4 = 12.

b) 2211  +12  =   2223
c) 3 x 4  = 12
d)  222 + 12 = 234
e) 4x 4 = 16
f)  23 + 16 = 39   which is divisible by 13.