Alien spacecraft are invading your planet against your defence of three laser weapons. The lasers can only be charged by answering mathematical problems correctly. Ten consecutive answers charge a laser sufficiently to enable an alien craft to be destroyed. Get one wrong, or take too long to answer, and you lose a laser.

The Mode 7 Teletext display is neat and well presented, but I think the battle scene could be a little more imaginative. The use of sound as the laser is charging would also add a little more excitement for the six to 16 year old to whom the program is aimed.

The options make this an extremely versatile program. There are 56 selectable grades with various combinations of addition, subtraction, multiplication and division. Positive and negative numbers, the time allowed for answers, the largest number to be dealt with and the number of parts in the questions can also be selected. Difficulty level can be constant or increasing.

Instructions are excellent. For kids who have to suffer computer maths there should at least be some enjoyment in this approach.

D.H.