I haven't gone through the formula because I am not on my system that has Excel at the moment, and besides, it wouldn't work without knowing the other data.
But in general;
* I assume that the first expression, " IF(ISBLANK(#REF!) " is intended? I know we can use ISERRORs to manipulate functions, but sometimes that #Ref! can mean an error in the formula.
* Excel only allows up to 7 IF statements in any formula. I don't know if that applies to Excel 2007 and 2010, but certainly prior versions. Your formula is OK though.
* Every IF function must have an open bracket and a closing bracket. So nested IF functions can be difficult to keep track of because they must be closed. That often means a number of close brackets at the end of the formula. Yours only shows 2 close brackets at the end.
Examples
=IF(C1=10,"CORRECT",IF(C10=5,"CLOSE",IF(C10=15,"TOO HIGH",IF(C10=11,"ONE OUT","INCORRECT"))))
I have 4 IF statements, of which 3 are nested. I need 4 closing brackets at the end.
* IF means, If this, then that, else something else.
I'm sure you know that already, but looking at your formula I can't see that this is following that rule. I broke it down like this;
a) =IF(ISBLANK(#REF!),
b) IF(ISNUMBER(I10),
c) IF(N10>=I10,N10*L10,N10*K10),N10*K10),
d) IF(ISNUMBER(I10),
e) IF(N10>=I10,N10*L10,N10*K10),N10*K10))
Doesn't c) end the function? that is, If N10 is greater than or = I10, then N10xL10, else, then N10xK10. You also have another 'Else' after that in N10*K10.
If there is an Else somewhere in the expression and that is not another IF statement, then the formula may end prematurely.
Some things for you to look into.
Mark
I am creating a purchasing form. The items have a sliding scale for pricing (the more you buy, the cheaper they are). So the Quantity price (N10) in the formula effects the total price. I have three different pricing amounts and can only get two to work. How do I add in the third IF statement to make it work? See formula below:
=IF(ISBLANK(#REF!),IF(ISNUMBER(I10),IF(N10>=I10,N10*L10,N10*K10),N10*K10),IF(ISNUMBER(I10),IF(N10>=I10,N10*L10,N10*K10),N10*K10))
Thank you for your help and let me know if you need more info.

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