Need formula to sequentially look in three columns and return calculation if column is populated.

[wsnow]

Column A, B, and C may or may not be populated. When they are, it is always a $ amount and always populated in sequence. First A is populated, then at a later date B is populated, then at a later date, C is populated.

I need a formula in column D that checks each column to see if it is populated and return a calculated amount based on the most recently updated field, starting with column C:

If C is populated, D should return the $ amount in C *.88.

If C is not populated, look in column B, and if it is populated, return the amount in B *.88.

If neither B nor C is populated, look in column A and if it is populated, return the amount in column A*.88.



If none of them are populated, D should return "".

This is my first stab at it and get a "too many arguments" error.

=IF(ISNUMBER([@[12-Month Lock-in Amount]]),( [@[12-Month Lock-in Amount]]*.88), IF(ISNUMBER([@[6-Month Estimate]]),([@[6-Month Estimate]]*.88), IF(ISNUMBER([@[30-Day Estimate]]),([@[30-Day Estimate]]*.88)),””))

Thanks.