40/66 as a percentage is 60.61%. This tells you that the fraction is a little more than half of a whole. When you see this number, you can picture a pie chart that is just over 60 % filled.
The fraction 40/66 can be reduced to 20/33, which still represents the same part of a whole. Both forms show the same size relationship, just expressed differently.
Knowing the percentage makes it easy to compare with other numbers. For example, if you have 60.61 % of a budget spent, you can quickly see how close you are to using up the whole amount.
