"T Harris" wrote:
Using 75 cells down begining with A1 and B1,
I have random number between 1-75 in B column
and corresponding letters of the word BINGO to
appear accordingly in the A column. [....] Now
when I hit F9, the BINGO results are displayed in
the first 75 rows of the A and B columns.
[....] How do I generate the 75 unique solutions
so that no duplicates appear in the first place?

How automatic do you want this to be? One
approach, following McGimpsey's suggestion
with an important correction:

A1: =MID("BINGO", INT((B1-1)/15)+1, 1)
A2: copy A1
B1: 1
B2: 2
C1: =RAND()
C2: copy C2

Copy A1:C2 (2 rows, 3 columns) down thru C75.
Note that B will contain constants 1-75.

Use Data Sort to sort A1:C75 based on C1.
Repeat this sort each time after you press F9.