In the Crystal Room you must do this on each crystal - select the god's (animal) icon, in the same relative position they are on the columns outside. Select the symbol (staff, water, etc.) that goes with each god. Select the correct number on each crystal, according to the formula. Observe the number on the column outside, then add or subtract, following the instructions on the parcment you found. This also assumes you have learned to read the numbers from the other parchment (the one showing knives, baskets, etc.) Notice also the colors.