- http://stackoverflow.com/questions/10984974/why-do-people-say-there-is-modulo-bias-when-using-a-random-number-generator
- https://zuttobenkyou.wordpress.com/2012/10/18/generating-random-numbers-without-modulo-bias/
The random numbers generated using modulo are biased. Check the above article.
The correct way of implementation is also specified above.