hello sir ,

it can be calculated by this logic,he percentage when put in simple words will convert the given value out of 100, instead of given total value.

Let me be more clear by taking your example,

You got 57 marks out of 80, Now if we try to take percentage of it, we will convert 57/80 into x/100

So Now we want both of this ratio to be same, as we want the 57/80(~0.7125) value to be same

⟹57/80=x/100

⟹x=(57/80)100

Hi dear,

You can't calculate your marks with the help of percentile because percentile indicates that how many students are ahead and behind you.Suppose your percentile is 85 that means you are ahead with 85 percent students appear in the exam.you can predict your rank as

Rank=(100-your percentile)×no of students÷100
Thank you