The game Multiply Aliens Attack is designed to help improve your ability to add and subtract quickly. The first think you do when playing the game is select the difficulty you would like to play on.
Beginner has you multiplying only small numbers. It is primarily for kids who have just recently learned how to add and subtract. The aliens move slowly, and there is usually only one on the game screen at a time.
The Intermediate difficulty has you both multiply and divide larger numbers than on the Beginner difficulty. You need to be able to divide numbers, and multiply numbers that have multi-digit answers. If your answer is more than a single digit (e.g. 12) type the number sequentially like you would into a calculator.
On the Advanced difficulty, the numbers get larger and the aliens come more quickly. You should play advanced if you are pretty good at arithmetic, but you would like to be able to improve the speed at which you can multiply and divide numbers.
Impossible is really difficult, and only should be chosen by players who are already really good at arithmetic. Play Impossible if you want to see just how good you really are.
When you start to play the game, aliens will begin to drop down from the top of the screen with Addition and Subtraction math problems above them. You must solve the math problem and type in the numbers on your keyboard. If there is more than one number (e.g. 10) just type it in like you would type it into a calculator. If you hit an incorrect number, an error will be displayed and you will get a score penalty. When the "Remaining" number in the top right of the game screen is 0, you will pass the level.
If you take too long, the aliens will drop bombs on your city. If your entire city is destroyed you will lose the game.