In the product details of this calculator, it states that there is a "decimal point selector." This is normally a slider starting with the letter F followed by the numbers 0123 etc. It is probably on 0. You can set the number of decimals to whatever you want, or use F for full numbers. For example, if you set this to 2, you should always get 2 decimals.
Without a manual, look at the picture of the calculator. Mount the paper, with the feed coming forward and over the top of the calculator. Insert the paper (recommend cutting it flush) into the feed slot in the back. Then use the paper advance key to advance the paper through the rollers. Unfortunately the manual is not available from the Staples website. Good Luck,