If it's a scientific calculator, press mode a few times until you see "Fix, Sci and Norm" in the display. Press whatever you need to press for Norm. If you get asked for 1 or 2, choose 2. This will give decimal answers all the time. 1 will put any numbers less than 0.001 into scientific notation.
If it's a graphic calculator, go to normal run mode, then press [Shift][Menu] (this is the "set-up"), then scroll down until you find "Display" and change it to Norm 2.
Hope this helps.