Consider all possible dates (formatted DD/MM/YY) within a span of a century , from 01/01/01 to 31/12/00 (20th century!).
In this period there are N k
dates that can be expressed by k distinct digits, e.g. N1
a. Derive the values of N k for all other values of k (2 to 6).
b. What is the average k for the 20st century?
c. How about the 21st century?
(In reply to computer-aided solution
Each of us committed an error, and it slightly affects your otherwise
a. I wrongly defined the 20 th century, shifting it forward a year.
b. You wrongly assumed that 2100 is a leap year, and it is not.
I would appreciate it if you modify your entry.