Division in Excel

[sgtbob]

I need to know how to add a string of cells and then divide by another string in MAC Office Excel 2008. e.g. =sum((B1:b10)/(b15:b20)) - Can someone show me where I am going wrong? If I use the =sum((b2+b2+b4)/(b20+b21+b22)), it seems to work, but how do I save myself some typing by using a series of cells?

Also, how do you 'copy down' a formula? I used to be able to highlight a cell in Excel 2003 and then 'ctrl + d' to do this, but can not find these things in Excel 2008. I have MAC Office 2008 Excel and need some advice.

Bob

[DonkeyOte]

=SUM(B1:B10)/SUM(B15:B20)

each range must be summed separately.

I don't have MAC so I can't offer further suggestions...

[oldchippy]

I don't have a MAC either

how do you 'copy down' a formula?

But can't you auto-fill down by the fill handle?

[berk21]

I sometimes just copy a blank cell with the formula and highlight the cells you want that formula in and paste...not sure if that is what you were referring to but thought I would let you know anyway..