Two mind-stretching games by Widgit Software.

Sum Vaders - armed only with mental power and nimble fingers you eliminate invading alien robots by adding or subtracting vital numbers. But the alien forces continuously speed up their invasion. Can you survive and save the world from a robot invasion?
Several levels of difficulty and a two-player game with a handicap option make Sum Vaders an equal challenge for all family members, from 8 years to adult.

Robot Tables - control a machine processing raw material into a sequence of perfect robots. Do you know enough arithmetic to set the machine to the right process? The automatic factory won't stop if you give the wrong instructions.
Several levels of difficulty and a choice of speed makes Robot Tales an ideal way to exercise multiplication tables both for early learners and more advanced children. Recommended from 6 or 7 to 12 years old and beyond.