This classic riddle looks like a subtraction problem, but the key is the phrase “all but 9”.
A farmer has 17 sheep. If all but 9 run away, that means every sheep except 9 leaves. You do not subtract 9 from 17. The wording already tells you how many remain.
Answer: 9 sheep.
The puzzle is designed to make people react quickly and calculate 17 − 9 = 8. But “all but 9” means 9 are the ones that did not run away. Reading the sentence carefully is more important than doing arithmetic here.


