How do I cut a 10″ square with my ruler?!

Answer:

To cut a 10″ square with your ruler (and I assume your board) try:
either 2 rulers to make up the 10″ and cut a strip: OR use your square ruler: OR cut a 10″ strip using the board to count and then cut across in the opposite direction (as you would smaller squares) but again using the board to count –

NB:  ALWAYS put your fabric to zero on the board and not to 1″ !!