Oh dear, is there nothing simpler?

I tried Jan Karel's solution.But first I ran into the problem that for some
reason my version of Excel demands German syntax, i.e. it does not
understand commas and demands semi.colons. Similarly, it demands dates to be
formatted tt, mm, jj, rather than dd, mm,yy, and to date I have found no
way to change this. However, the help screens use English syntax!

Anyway,having entered the modified formula, when I dragged it down the
column, it simply repeated itself, and did not adjust for b, c, etc.

I am a beginner as regards VBA programming, which is why I sent my query to
this newsgroup rather than the excel programming group. But Gord Dibben's
solutions I find useful ,especially as the syntax regarding changing
absolute to relative formulas or vice versa.