If it's 4 o'clock, the hour hand will be on the 4 and the minute hand will be on the 12.
This takes 4 partitions/pieces of the clock, and there are 12 different partitions. That's 4/12, or 1/3 of the entire clock.
The total clock is a 360 degree angle.
360 * (1/3) = 120
1/3 of 360 degrees is 120 degrees.
Since the angle between the minute and hour hand takes up 1/3 of the clock, the angle is 120 degrees.
Let me know if you need any clarifications, thanks!
