How many hours is 9am to 1am?

Let's try a number line using military time. Nine o'clock AM is 0900, and one o'clock AM is 0100. So, we start at 0900 and count to 0100:

0900-1000-1100-1200-1300-1400-1500-1600-1700-1800-1900-2000-2100-2200-2300-0000-0100

We get 16 hours. Another way you can do this is simple math.

We know that 0100 is an hour after midnight, and 0000 is midnight. So, take 2400 (another way to look at midnight), and subtract 0900:

Simplified it is 24 - 9 = 15 + 1 = 16

9AM to 1AM is sixteen hours.