How do I calculate percentages on excel?

Suppose this scinario:

A1: $25 | B1: $120 | C1: 20.8333

Type "=A1/B1*100" in C1, where A1 refers to the number in cell A1 and B1 refers to the number in cell B1. In this example, we are calculating the percentage of A1 in B1. If you copy and past the formula down the column, Excel will automatically change the cell numbers. "=B1/A1*100" will give you the percentage of B1 in A1, in which case the answer would be 480%.

For many other functions, go to "Formulas" tab and look under "Function Library".

It depends what version it is, I use MS Office Pro 2010 and all I do is click auto formula and it self calculates, I hope this is of some help to you. Regards

B1 =A1/SUM(A:A) format as % then copy down to match col A.