This package by Mirrorsoft contains two games for youngsters, Sum Vaders and Robot Tables. Both programs are designed to give practice in number skills.

Sum Vaders requires you to use some quick thinking to stop the invasion of robots. Addition, subtraction, multiplication and division problems are presented and you have to get the answer right first time. An alien spacecraft bearing a number moves across the screen. It releases a robot invader which also has a number.

The object of the game is to destroy the robot before it reaches the ground. To do that you have to type the correct response to the sum. In the addition option, you have to add the two numbers, while the subtraction option has you taking the smaller number from the larger.

The product is entered in the multiplication option and the smaller number is shared into the larger in the division option. As your skills increase, so does the difficulty, the attackers coming in lower and faster. Your turn ends when five aliens get past and land on Earth.

There are five levels of difficulty for the adding and subtracting options. Only three levels are available in the multiplication and division options.

A nice feature of this program is that two people can play in competition, each player at his own level of difficulty. This enables a child to compete with an adult, yet still be able to win. In the two-player game, high scores are separately recorded.

The second program, Robot Tables, is based upon a manic machine designed to frustrate the would-be mathematician. The aim of the exercise is to create robots - in contrast to Sum Vaders, where the object was to destroy them.

The robots are produced from lumps of raw material that is fed in from the left-hand side. Each lump contains a number. You have to decide whether that number is the next one in the sequence that is displayed below. If you reject good material - a correct answer - or if you accept bad material - a wrong answer - the machine makes a damaged robot.

If the material is OK and it is accepted by you, a perfect robot is produced. If you correctly reject bad material, it's recycled. Points are credited for material recycled and each undamaged robot produced.

Bonus points are given for every sequence of ten robots that are created. There are two modes for the game - learning and testing. In the learning mode the correct sequence of numbers is first displayed. There are much longer response times and answers are displayed after each robot is made.

The testing mode is much faster and points and lost for incorrect responses. I'd be happy to use the programs with most youngsters.

John Woollard