Level 3 spreadsheeets

I had to look this up...because my own version of Excel (Excel 2000) seriously predates this particular function being introduced! xD

Basically, an array formula is a single formula that works on an entire set of cells, and and collects a set of formulae together.

Say you have two columns of data in your spreadsheet - column A is quantity, column B is unit price.

Normally, to work out totals of each item, the cells in column C would have the formulae:

=A1*B1 (for C1)
=A2*B2 (for C2)
=A3*B3 (for C3)
...and so on. Let's say there were 100 different items. The last one would be =A100*B100

But instead, an array formula would collect all of these into one, as follows:

=A1:A100*B1:B100

This formulae is telling Excel to mutiply the first cell in the first range (A1) by the first cell in the second range (B1), then doing the same with the second cell in each (A2*B2) and so on, down to 100.

I hope that helps.