How to calculate percentage?

Calculating percentage of a number is very simple,

If I got 42 out of 50 marks in my exam, How much percentage of marks did I  get?

Marks scored= 42
Total marks=50

Percentage of marks = (Marks scored/Total marks)*100

That is, (42/50)*100=0.84*100= 84%

In the same way you can calculate percentage of any fraction.