How did this happen? of the week.

I'm in Microsoft Excel. I'm trying to divide 1050 by 12 to come up with a monthly cost of a particular item. So I click on a cell, type a "=" (which, if you don't know, starts an Excel formula), follow that with a "1050/12", and hit "Enter." My result: -3.166667. How did this happen? (Hint: I figured out the answer right away, but I had help.)