madbloke wrote:
I'm currently checking for duplicate entries in a sheet by using data
validation - =ISNA(VLOOKUP($C53,RANGE1,1,FALSE)), so that if a
duplicate is entered, it brings up an error message.

What I want to do is extend this to include other ranges i.e.
=ISNA(VLOOKUP($C53,RANGE1 RANGE2 RANGE3 etc,1,FALSE))

Is this possible? And if so, how? I've tried commas, semicolons,
colons, but nothing seems to work.

=OR(ISNA(VLOOKUP($C53,RANGE1,1,FALSE)), ISNA(VLOOKUP($C53,RANGE2,1,FALSE)),
ISNA(VLOOKUP($C53,RANGE3,1,FALSE)))