Multiply by percentage

if it's just one cell and one percentage you need to do this for, assuming the number you want to add the product of your multiplication to is in A1 you could just use =(A1+(100*.2))
i have a feeling you'd like to be able to do more than one cell though so if that's the case could you give some more details and i'll try to help you further -there are a few ways you can lay out your worksheet to make things a bit easier.

Or simply.....

=A1*1.2

Alternatively, you could enter 1.2 in any blank cell (say C1), select C1, copy, select the cells you want to increase, PasteSpecial/Multiply, delete C1.

Won't the formula =(A1+(100*.2)) merely increase the value of A1 by 20, instead of by 20% ?

...the formula i gave was based on the numbers in the original request, which i initially didn't read to mean multiply by 20%. my first read was that vicki had a percentage (20%) and a value to multiply it by (100) which she then wanted added to a value in another cell (cell A1 in my reply). looking again i can see another interpretation, which john's post solves. =A1+(A1*$X$0)is another option, with '$X$0' being a separate cell to enter the percentage in, which allows you to change the percentage without changing every formula, if you have many numbers to convert.