How to find whether a large number is divisible by 13 ?

How to find whether a large number is divisible by 13 ?

Lets take an example : Is 377 divisible by 13 ?



Here is trick


37  -  9(7)  =  37  -  63  =  -26


As -26 is divisible by 13  we can say that 377 is also divisible by 13...



Lets take another example  :  Is 2054 divisible by 13 ?



Therefore


205  -  9(4)  =   205   -  36  =  169


Again



16  - 9(9)  =  16  -  81  =  -65



As -65 is divisible by 13 ... The number 2059 is divisible by 13...



Note :  Multiply the unit's place with 9 as in both the above examples....

Posted in: Division, Maths