Adding

This is a great website to practise mental addition:

http://funschool.kaboose.com/formula-fusion/games/game_addition_attack.html

This is a robot adding game:

http://funschool.kaboose.com/formula-fusion/number-fun/games/game_dr_brains_robot.html

Another fun adding game:

http://funschool.kaboose.com/formula-fusion/number-fun/games/game_cannon_math.html