This is kinda hard to explain but I'll try my best. Here's a tip, the fractions that are on the ruler really mean 10,20,30,40,50,60,70,80,90, and 100. So, when you look at the decimals on number 7, you have to try to turn them into fractions in your head. For example, 0.9 is actually 9/10 or 90.
