A farmer builds a straight fence 100 meters long. He places a wooden post at the very beginning and another at the very end, then spaces posts exactly 10 meters apart along the entire length. How many total posts does he use?
11
Dividing a 100-meter fence into 10-meter intervals creates 10 segments (100 / 10 = 10). Because there is a post at the start of the first segment and one at the end of every segment, the number of posts is always one greater than the number of segments. 10 + 1 = 11 posts.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Easy. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
More logic riddles
An old manuscript contains a four-digit code. The sum of all four digits is 10. The product of the first two digits equals the product of the last two digits, which is 6. The third digit is greater than the fourth. What is the code?
If 1 cat can catch 1 mouse in 1 minute, how long would it take 100 cats to catch 100 mice?
Five friends line up for a ride at the fair, and the sign lists only these facts. Felix stands ahead of Mara. Mara stands ahead of Boris. Kira stands ahead of Luca. Luca stands ahead of Felix. Who stands third in line?
Tom is older than Bob. Bob is younger than Sam. Sam is older than Tom. Who is the youngest of the three?
In a strict digital vault, a security guard checks employee badges using a color sequence. Red always follows Blue. Green never directly follows Red. Yellow must always come immediately before Green. If an employee presents a badge sequence of Blue, Red, Yellow, Green, which rule is violated?
A king places a hat on the heads of three wise men chosen from a set of 3 white hats and 2 black hats. None can see their own hat, but each sees the other two. The king announces at least one white hat is present. He asks who knows their hat color. After a long period of silence, one wise man correctly states his hat color. What color is it and how did he know?