This riddle says: “I add 5 to 9 and get 2. How can that be correct?” In ordinary arithmetic, 9 + 5 is 14, so there must be another way to interpret the numbers.
The answer is a clock.
If it is 9 o’clock and you add five hours, the time becomes 2 o’clock. Count forward: 10, 11, 12, 1, 2.
So on a 12-hour clock, adding 5 to 9 really can give 2.
The riddle works because it makes you assume the numbers belong to standard arithmetic. Instead, they represent hours on a clock, where the numbers repeat after 12. Once you switch from ordinary addition to clock time, the statement is perfectly correct.
