If you have a calculator with you when you are using a photocopier to enlarge or reduce, you can figure it out yourself. For example, if you want to make a 6" block larger, to 8", you divide 8 by 6 and get 1.33. That is the percentage you put into the screen on the copier: 133%. You do the opposite for reducing. Same example: the block is 8" and you want it to be 6". Divide 6 by 8 and get 0.75. You put 75% into the screen and print that.