I have this formula, which works quite nicely

sum('usd begin:usd end'!m10)

to automate it, I started setting local names in the spreadsheet so I can
use the sheet more than once.

so sheet1!currency=sheet1!$b$3 for example.

So in sheet 1, a made this formula

=sum(indirect("'"&currency&" begin:"&currency&" end'!"&CELL("address",M10)))

alas, I have a ref error. I checked the string and it was fine. Any
suggestions?