Not sure what you want but this has syntax errors:
IF(ISBLANK(A1),C1,OR IF(A1B1,A1-B1,OR IF(A1<B1,B1+C1),OR IF(A1=B1,B1),"")
Try
=IF(ISBLANK(A1),C1,IF(A1B1,A1-B1,IF(A1<B1,B1+C1,IF(A1=B1,B1,""))))

The syntax of IF with two nestings is: IF(condition_1,
true_answer,IF(condition_2,true_answer, false_answer)
This of IF..ELSE rather than IF..OR

OR is used like this: =IF(OR(A1<3,A110),"A1 is out of range","A1 is within
3-10")

best wishes
--
Bernard V Liengme
Microsoft Excel MVP
www.stfx.ca/people/bliengme
remove caps from email

"Working Jane" <Working wrote in message
...
I want a formula to make another evaluation based on answer to the previous
evaluation(s); i.e. if answer to 1 is 0, then do next eval; if answer to
second eval is 1, then do next eval and so on. It should stop at whatever
eval gives the desired result before defaulting to "do nothing" ("").
Years
ago I could use the OR function to do this, now OR is inadequate. Nested
IF
functions can get too cumbersome (if FALSE do this, if TRUE do that for
each
evaluation). Likewise with VLOOKUP or HLOOKUP. Would like a suggestion,
for
example, "IF(ISBLANK(A1),C1,OR IF(A1B1,A1-B1,OR IF(A1<B1,B1+C1),OR
IF(A1=B1,B1),"")." Need something like the old OR function, which was
good
for evaluating a large range of variables not necessarily in a table and
in
search of a specific value(s). Hoping for a new or better or other
function
in Excel that I'm not aware of, or just a new perspective on how to better
use an existing function. I do these types of evals often at work and the
build on successive IFs can take hours to perfect or stop the input at
"too
many variables."