How to make a mathematical formula operate in the same cell in which I input a number?

I have students doing an exam of 53 questions.

When they tell me the score, eg. 46 out of 53 questions correct, I want to put that number into a cell, and then have it automatically convert it to a percentage in that same cell. Is there a way to do this in the same cell into which I input the number?

example. in Cell B3.

I put in the number 45.

Excel makes a calculation of "45 divided by 53 multiplied by 100" and puts the result as a percentage in the same cell (B3) where I input the value 45, in this case 86.79%.

I know how to do this using more than one cell, where the formula is put in to cell B4, which would tell excel to take the value of cell B3, apply the formula, and get the result in cell B4. I am trying to find out if I can do it inside the cell without additional cells and external cell references.

Thanks!