Click equals to get points. Click minus to upgrade. When you do this it will ask you for a number. You can not enter numbers that are higher than your score or not multiples of 100. 100 is one more plus power. You can also play this game with a real-life calculator if it doesn't show symbols. If playing on a calculator you also have to not cheat and enter the plus power yourself.
Credit to my calculator in maths class. If numbers don't show, press the green flag again. I will add more backgrounds later.
