a pass word is 4 letters followed by 1 digit. uppercase letters (A) and lower case letters (a) may be used and are considered different. how many passwords are possible.

Answer 1

Assuming the letters can be repeated, there are 52 choices for each of the first four positions; then the digit can be one of 10 choices 0...9: 52⁴ * 10 = 73,116,160 possible passwords

If letters must not be repeated then you get: 52*51*50*49*10 = 64,974,000 possible passwords