I am glad to invite you to Infinitum April'14, a monthly contest restricted to mathematics domain, held on HackerRank.
Register at https://www.hackerrank.com/infinitum-apr14
It's a 4 day contest with 6 problems with problem statements in English, Russian and Chinese.
You can view the last month's challenges here: https://www.hackerrank.com/infinitum-mar14/challenges
This month, the problems are much more interesting, have more variety and are a little more difficult.
Looking forward to a great participation! :)