Here are some useful sites to keep you on your toes.
1. http://www.bbc.co.uk/skillswise/game/ma25time-game-hours-vs-minutes
2. http://www.bbc.co.uk/skillswise/game/ma25time-game-24-hour-snap
3. http://www.teachingtime.co.uk/draggames/sthec5.html
Mental Strategies:
1. http://www.woodlands-junior.kent.sch.uk/Games/educational/maths.html
2. http://www.sheppardsoftware.com/mathgames/quickmath/quickmath.htm
3. http://www.sheppardsoftware.com/mathgames/quickcalc/quickcalculate_1.htm
Who wants to be a millionaire??: