Step 1: Press a or b for simple or compound. Doesn't matter if it's capital or not. Step 2: Enter in the principal. Principal is the money you put in the bank. Step 3: Enter in the rate. Rate is the percentage your money increases, but please enter in decimals. Step 4: Enter in the time, in this case, years. Time is the amount of time you keep in there. Enter all of them in and bingo, you get the interest. It only tells you how many extra money you earn, not the amount you get after putting your money in.
DON'T use it to cheat on your math homework. DO use it for saving time IF you want to check WHAT you got wrong in your math homework. DO use it for saving time IF you have a bank account. For people who do not like calculating too much. If you are too lazy to type in a few keyboard symbols, maybe you really are lazy.
