# Excel 2010 - want to multiply numbers without typing excessively

I have a column B, so my data is from B1 to say B500. I want C1 to be B1

C2 to be B1*B2.

C3 to be B1*B2*B3

C4 to be B1*...*B4 ...

C500 to be B1*...*B500

Is there an easier way to do this rather than typing the formula manually? I think I can use the function PRODUCT, but I would still have to type the rest of the references manually. Anyone has a more elegant solution?

-

Yes, you can use the PRODUCT() function, passing a range of cells as an argument. Simply enter the following into C1:

=PRODUCT(B$1:B1)  Then drag the formula down (by grabbing the small square at the bottom right of the cell highlight rectangle). The $ means an absolute address, so the start of the range remains at B1 while the end is extended for each new row that you drag the formula to - for C2 it'll become B$1:B2, for C3 it'll become B$1:B3, and so on.

Alternatively, if the numbers in B1-B500 are sequential from 1 to 500, you can use the FACT() function (which calculates the factorial of a given number) to achieve the same thing.

-

Here's how I do this sort of thing:

• In C1, I set =B1
• In C2, I set =B2*C1
• In C3 through C500, I make it a copy of C2, by selecting a box and using Ctrl+D.

When Excel copies formulas, it uses relative addressing, unless you tell it not to.

So C500 ends up with a formula that says =B500*C499.

-