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# How to calculate product of a sequence?

Please see attached image in order understand this very simple question:

Column K contains the formula I'm trying to figure out. I'm having to manually input these formulas and I'm trying to figure out a quick way to do it.

K52 =PRODUCT(1-J52)
K53 =PRODUCT(1-J52,1-J53)
K54 =PRODUCT(1-J52,1-J53,1-J54)

K55 should be = PRODUCT(1-J52,1-J53,1-J54, 1-J55)
...and so on...

Please let me know what would be a quick way to copy this formula down till row K127? Thanks.
Product-Sequence.JPG
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Inciteful
1 Solution

Commented:
K53 = PRODUCT(K52, 1-J53)
K54 = PRODUCT(K53, 1-J54)

and so on.

Ss
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Commented:
Try this version

=PRODUCT(1-J\$52:J52)

confirmed with CTRL+SHIFT+ENTER and copied down

Barry
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Commented:
While both sshah254 and barryhoudini formulas work, you may prefer to dispense with PRODUCT altogether and copy down the following formula in cell K53
=(1-J53)*K52
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Author Commented:
Barry - i like your formula best.

One question though...

If I want to copy this formula across COLUMNS on another worksheet ? How would I set up the formula so that the references continue to work?

(Say the sheet in the image is called "sheet1")
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Commented:
The \$ fixes the row reference (makes it absolute) in the above so that when you copy down the J\$52 remains J\$52, if you want to copy across then it's the same principle but you use \$ in front of the column letter so if you wanted to start with B4 and then add C4, D4 etc. you could use

=PRODUCT(1-\$B4:B4)

then copy across

regards, barry
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Commented:
Oh, I missed the sheet part, if that was on another sheet it would be like this

=PRODUCT(1-sheet1!\$B4:B4)

still confirmed with CTRL+SHIFT+ENTER

....although if you want to avoid "array entering" you could add an INDEX function like this

=PRODUCT(INDEX(1-sheet1!\$B4:B4,0))

regards, barry
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Author Commented:
Barry - when i copy that formula across columns A to Z the references dont change appropriately...
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Commented:
OK, I assumed you wanted to now make the references go across too, so you'd get the product of 1-B4 then the product of 1-B4, 1-C4 etc. but do you mean you want to copy the formula across but the references still go down?

If so then you can use OFFSET, e.g. if your data is on worksheet data then put this formula in B4, confirmed with CTRL+SHIFT+ENTER and copied across

=PRODUCT(1-OFFSET(data!\$J52,0,0,COLUMNS(\$B4:B4)))

change B4 reference depending on your start cell

see attached, notice that the vertical results in Data sheet are the same as the horizontal ones in sheet1

regards, barry
26848133.xlsx
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Author Commented:
thanks!
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