To transfer a faction to a percent like this we can add a 0 to the 10 to make it 100 and a 0 to 9 to make it 90. In this case, the number is simple number rather than a decimal or something else more complicated that you might learn later. 90 of 100 is simplified to simply transferring 90 to 90% of 100 so the same goes for 9/10, 9 is 90% of 10.
