Office said:

I need to calculate the percentage of a number in a specified period. Can

excel calculate a percentage of an occurence?

Not sure what you mean. It would be better to provide a numerical

example.

If you want to compute 10% of a number in A1, then simply:

=A1*10%

If you want to compute what percentage B1 is of A1, then:

=B1 / A1

If you want to compute the percentage difference between A1 and B1,

then:

=B1 / A1 - 1

(Caveat: For the latter two, A1 and B1 must both be positive or both

be negative. And A1 cannot be zero.)

In all cases, format the cell as Percentage with the desired number of

Decimal Places. Click on Format > Cells > Number and select Percentage.