So, looking at the definition of noon it says it's twelve o'clock...
Now lets do the math - starting from 9 and working until 12 is 12-9=3 hours.
Well, maybe I got something wrong:
9 -> 10 = 0 + 1 = 1 hour
10-> 11 = 1 + 2 = 2 hours
11-> 12 = 2 + 1 = 3 hours
How on earth can I trust someone writing this kind of lengthy blog post if he cannot even get the simple math right. I wouldn't complain if it was a bit smaller issue - but the whole article is talking about 4-hour workday that starts from 9 and ends at noon :)