I used to live off of excel from the 1st week it came out till about 11/2 years ago. I still design my own spread sheets for the stock market, an options program, and other things.

When you want to do something just put your cursor where you want the answer to show up. The click on the = sign, move mouse over to cell A1 click on it then click on - sign and then click on cell B1 and then hit enter. Like magic it is done with typing the cell names or numbers.