I have an column of numbers, e.g.

a1 - 0.03
a2 - 0.17
a3 - 0.35
a4 - 0.54
a5 - 0.67
a6 - 0.83
a7 - 1.00


What I'd like is a formula that returns the cell reference of the first
number in the column that is above a specific number (say, 0.5). Can anyone
suggest a formula that would achieve this?

Many thanks,
Geoff.