RoomRecess one of my favorite sites around for free online educational games, has a Math page dedicated to K-5 students. This page has a number of different style games such as: RPG, platform, sports, etc. to help students learn and keep them engaged in this fun way. Best of all, Elementary students can find a wide range of Math topics from addition and subtraction, to decimals, fractions, and making change, and much much more.
I highly recommend checking out RoomRecess Math Games by clicking here!!!