one way:

InC1: =A1&B1 and copy down

in D1: =SUM(1/COUNTIF($C$1:$C$6,$C$1:$C$6))

Enter with Ctrl+Shift+Enter

HTH

" wrote:

I have a two columns A with surname and B with first name, but entered
multiple times:

eg:

Smith, John
Smith, John
Smith, Arthur,
Rabbit, Peter,
Rabbit, Peter
Rabbit, Peter

What's the easiest way to total up the number of people there are? In
this case 3.

Thanks