hm,
When you say the data ends in M2 i assume it's the numbers to the left of
the M you want to sum. If so try this
=SUM(VALUE(LEFT(A1:A10,FIND("m",A1:A10)-1)))
Which is an array so commit with Ctrl+Shift+Enter NOT by pressing enter. If
you do it correctly then Excel will put curly brackets {} around it. You cant
type this yourself.
If its the numbers to the right of the M then use this. Once again an array.
=SUM(VALUE(MID(A1:A10,FIND("m",A1:A10)+1,LEN(A1))))
Mike