Problem with concatenate function in google sheets - google-sheets

Question

So I am trying to recreate something like this picture:
Financial Year in excel
But I just found out that the cell B7 does not work, the cell B7 contains the formula:
=IF($A$3="Financial Year",((CONCATENATE(B9,$C$3))-DAY(CONCATENATE(B9,$C$3))+1),EDATE(Summary!$C$15,-11))
In the above A3 cell is the one where I choose Financial Year, B9 is month January, C3 is the cell with the calendar year 2020 and the Summary tab is the picture here:Summary Tab where cell C15 is the starting date with the formula: =EOMONTH(TODAY(),-1)+1
Error I am getting from Cell B7:
Function Day Parameter 1 expects number values. But "January" is a text and cannot be coerced to a number

Answer 1

You may have had a temporary condition where C3 was blank. It is easy to run several tests to see what Day does with "Strings".
=Day("January" & 2020) returns 1, the day value of the first day of January.
=Day("January2020") also returns 1, even though "January2020" is clearly a string.
=Day("Nothing2020") returns the error you saw, where DAY expects a numeric value.
If the string is one that Google Sheets recognises as a date type, it treats it as a number value for those functions requiring that.
"January2020" is seen as a valid date, but "January" is not.
Your error indicates to me that C3 was blank at the time of the error, since it said {
"January" is a text, and cannot.....} .
Let us know if you still have the error situation. If so, please share a copy of your sheet.