IF Formula

I need help!

I have a worksheet with 100 entries on it each entry is a transaction. One column indicates if the transaction is closed or not (Yes or No). I need to write a formula that will allow me to add up the transaction amounts depending on if the transaction is closed (YES). I was thinking that I could use IF but cannot figure out how to use it for the entire worksheet.

Any help is GREATLY appreciated.

Use the sumif() function. It allows you to specify what to sum and the condition to use - "yes" in the column you are using. It should be exactly what you need.