Riddle:
A new medical building containing 100 offices had just been completed. Mark was hired to paint the numbers 1 to 100 on the doors. How many times will Mark have to paint the number nine?
Show Hint
Hint:
Add all the numbers that end in 9 and then add 90-98.
Show Answer
Answer:
20!
These are the doors: 9, 19, 29, 39, 49, 59, 69, 79, 89, 90,
91, 92, 93, 94, 95, 96, 97, 98, 99.