# Simple Sum formula not working

I'm running into an issue where it appears the formulas that I have returning a number are not available for simple math in sum formulas. Any suggestions?

For example, I have a column that produces the month a project will close based upon the estimated completion date currently linking in from the individual task lists. I have another column returning the month as a number, and am trying to subtract this from 12 and keep receiving "invalid operation".

Here is the formula I have running for the month to number conversion

=IFERROR(IF([Month Closing]@row = "Jan", "1", IF([Month Closing]@row = "Feb", "2", IF([Month Closing]@row = "Mar", "3", IF([Month Closing]@row = "Apl", "4", IF([Month Closing]@row = "May", "5", IF([Month Closing]@row = "Jun", "6", IF([Month Closing]@row = "Jul", "7", IF([Month Closing]@row = "Aug", "8", IF([Month Closing]@row = "Sep", "9", IF([Month Closing]@row = "Oct", "10", IF([Month Closing]@row = "Nov", "11", IF([Month Closing]@row = "Dec", "12", "")))))))))))), "please check")

and the formula that should be simple but apparently hates me:

• Try removing the sum function. The sum function only adds values that are separated by a comma. Simple math can be done without it.

• The other problem is the quotes around your numbers in your IF statement.

11 will return the number 11.

"11" will be displayed the same but is treated as a text string. Since text can't be summed, it will return an error.

• Good catch Paul! Yes, If you are trying to return a number value, never use quotes!!!

• Were you able to get this working?

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