Take all the Roman numbers (using the modern standard subtractive notation in which IV = 4, IX = 9, XL = 40, XLIX = 49, XC = 90, etc.) from I to M (1 to 1000)...

1. Which number has the most Roman letters?

2. If you group them by the number of Roman letters, which group has the most members?

3. How many numbers start with C?

4. There is something interesting about the groupings in #2. What is it?