Combining IFERROR and IF formulas

I have one column A with Forecasted numbers, and column B with Actual numbers.

I am trying to create an accuracy formula, which takes in consideration 0's.

This is what I have:
=IFERROR((A1/B1),"0%") I need to do an IFERROR, because some numbers in column A or B are "0's), and since we can't divide into 0's, the error will be replaced with 0% accurate.

So if I forecasted 0, and sold 2, the above formula will throw "0%"
If I forecasted 2 and sold 0, the above formula will also throw "0%".

However, when columns A and B both contain 0's (I forecasted 0, and sold 0) I will get a "0%". In this case, forecasting 0 and selling 0, should be 100% accurate. So I wanted to incorporate:

IF(A1=B1,"100%") into the IFERROR formula.. but I can't do it. Excel says that I have entered too many arguments,
when I enter: =IFERROR((A1/B1),"0%",IF(A1=B1),"100%"))

Any thoughts on how to combine these two? maybe I'm not combining them properly.

Any help will be appreciated!
(I'm using Excel 2007)

Try

=IF(B1=0,IF(A1=0,100%,0%),A1/B1)

Jonmo, I just tried the above formula, but it gives me a #DIV/0! error, when both numbers are 0

I see what you did. My column "B" (really in "J") numbers is being acquired by the following formula: =IFERROR(VLOOKUP(J10,A:H,8,FALSE),"0"). Where I forced a 0 in case it couldn't find the "part number" in the array. (my array for the vlookup does not necessary have all the part numbers).
So in this case, a 0 shows up, but not as a number, therefore the DIV error. How do I change the whole column into an actual number? or, how do I incorporate that into the vlookup formula?

Your formula worked, when I manually erased the "0" (derived from the vlookup) and manually typed the number "0".

Just remove the quotes from that formula so that it returns a numeric 0, instead of a text 0
=IFERROR(VLOOKUP(J10,A:H,8,FALSE),0)

Whoa! Perfect, thank you so much for your help and time.
Now, I will try to decipher " =IF(B1=0,IF(A1=0,100%,0%),A1/B1) " and try to analyze what you did here- still a newbie at formulas/nesting.

It would be cool to understand fully the logic, would you be able to break it down for me?

Thank you!!!!

If has 3 parts.

1. Expression (a question with true or false answer)
2. What to do If Expression is True
3. What to do If Expression is False

You can Nest another IF insede either part 2 or 3.

So the Red Part is the "what to do if true" of the IF B1=0
The Blue part is the "what to do if False" of the If B1=0
=IF(B1=0,IF(A1=0,100%,0%),A1/B1)

So if B1 DOES NOT = 0, then it goes straight to the A1/B1
If B1 IS = 0, then it asks is A1=0, if true (this means A1 and B1 are both 0) then 100%, otherwise 0%

Hope that helps.

Ah! I was confused because we were only looking at B1 first, and not if A1=0. But it makes sense, because you can't divide my 0, but you can have a 0 value and divide but something else.

Right, only A1/0 causes DIV/0 error.
0/B1 is NOT an error,