have you tried a countif formula. It will look if something exists on sheet 2 from what is on sheet 1. =countif('sheet2'!A:A,'sheet1'!a1)

This will count how many times that record exists. as far as nesting formulas it is easy to get comfortable with this by watching the tooltips.

For example when writing an if statement you start with =if(
now the tool tips will tell you that you are writing the condition. then you press a comma and it asks for what you want if the condition is true. You can put another formula in here if you want. try a sum write =if(a1=9,sum(6+3),sum(6-3))

Notice the last parentheses to close off the original if formula. It is very good to get comfortable with nesting functions. give it a shot and let us know what you come up with.