If you take the square root of 108 you’ll get 10.39 so the nearest tenth would be 10.4
If it helps the number stays the same if it’s under 5 and if it’s over five it goes up a number. For example if you have 34.62 it would just round to 34.6 but if you have 34.67 it would round to 34.7. It works with all decimal places.