Question

If passwords may contain lower case letters and digits, how many 6-character passwords start with a lower case letter a or ends with a lower case letter z.

Is the answer the following?
(36^5 + 36^5) - (36^4) = 119252736

Answer 1

why did you subtract 36^4?

Answer 2

the answer is right, but many people did it wrong by adding 36^4 instead

Answer 3

hmm 36^5 is for start with a or end with z, but there is a 3rd condition which is aXXXXz so i minus 36^4

Answer 4

that's correct. There is a theorem for that.
|A or B| = |A| + |B| - |A and B|

Answer 5

I see.