0It's a magic trick. So, here we go:
Think any three digit number and repeat itself twice like this: 123123.
Now, divide this number by 13, whatever the quotient has come divide it by 11. Again divide the quotient by 7, now the result in front of you is the three digit number that was originally taken in starting. Isn't it a magic?
So what we concluded is any three digit number when repeated twice will always be divisible by 7,9 and 13.
Enjoy and show this magic to others.
Thank You,
Vikash
