How many different twotwo-letter passwords can be formed from the letters
Upper A, Upper B, Upper C, Upper D, Upper E, Upper F, Upper G and Upper H
A, B, C, D, E, F, G and H
if no repetition of letters is allowed?

Step-by-step explanation:

GIVEN: two two-letter passwords can be formed from the letters  A, B, C, D, E, F, G and H.

TO FIND: How many different two two-letter passwords can be formed if no repetition of letters is allowed.

SOLUTION:

Total number of different letters

for two two-letter passwords different are required.

Number of ways of selecting different letters from letters

Hence there are different two-letter passwords can be formed using letters.