At the top of your screen are several target numbers. Use the red, green, yellow and purple numbers to make each target number. Each color correponds to a different mathematical operation. If you drop a number of one color onto another, the mathematical operation of the dropped number is used (so if you drop x3 onto +2, the answer will be 6, but if you drop the +2 onto x3, the answer will be 5.)

The puzzle is only solved when all of the numbers have been made. Use your mouse to stack numbers.