Drag down a formula which uses multiple columns?
 

Hi,

Banters the name, Excel is the game.

got a another problem Boy$.

I'm working out an average of a Column B.

To do this I need to work out each row as Column A multipled by Column B. Add these up and divide by the sum of Column A.

the Formula being (A1*B1)+(A2*B2)... /(A1:A300)

I may be being very dense here but is there anyway to copy this formula down rather than having to manually enter all 300 iterations of A1*B1, A2*B2 etc.

Thanks! :)