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Math Riddles

Logic Games And Riddles

Riddle 1)

How can you add eight 8's to get the number 1,000? (only use addition)

Answer

2) Two Fathers and Two Sons Riddle

Two fathers and two sons sat down to eat eggs for breakfast. They ate exactly three eggs, each person had an egg. The riddle is for you to explain how
How to Explain the Riddle

3) Digit Frequency

Part I. What digit is the most frequent between the numbers 1 and 1,000 (inclusive)?
To solve this riddle you don't want to manually do all of the math but rather try to figure out a pattern.
Answer to Riddle

4) Three Guys at A Hotel Riddle

Three guys rent a hotel room for the night. When they get to the hotel they pay the $30 fee, then go up to their room. Soon the bellhop brings up their bags and gives the lawyers back $5 because the hotel was having a special discount that weekend. So the three lawyers decide to each keep one of the $5 dollars and to give the bellhop a $2 tip. However, when they sat down to tally up their expenses for the weekend the could not explain the following details:
Each one of them had originally paid $10 (towards the initial $30), then each got back $1 which meant that they each paid $9. Then they gave the bellhop a $2 tip. HOWEVER, 3 • $9 + $2 = $29
    The guys couldn't figure out what happened to the other dollar. After all, the three paid out $30 but could only account for $29.
Can you determine what happened?
Answer to Riddle

5) Foreign Country Riddle

In a certain country ½ of 5 = 3. If the same proportion holds, what is the value of 1/3 of 10 ?
Answer

6) The Merchant

A merchant can place 8 large boxes or 10 small boxes into a carton for shipping. In one shipment, he sent a total of 96 boxes. If there are more large boxes than small boxes, how many cartons did he ship?
Answer

7) Crossing the River

A farmer is trying to cross a river. He is taking with him a rabbit, carrots and a fox, and he has a small raft. He can only bring 1 item a time across the river because his raft can only fit either the rabbit, the carrots or the fox. How does he cross the river. (You can assume that the fox does not eat the rabbit if the man is present, you can also assume that the fox and the rabbit are not trying to escape and run away)
Answer

8) Three Brothers on a Farm

Three brothers live in a farm. They agreed to buy new seeds: Adam and Ben would go and Charlie stayed to protect fields. Ben bought 75 sacks of wheat in the market whereas Adam bought 45 sacks. At home, they split the sacks equally. Charlie had paid 1400 dollars for the wheat. How much dollars did Ben and Adam get of the sum, considering equal split of the sacks?
Answer

9) The Insurance Salesman

An insurance salesman walk up to house and knocks on the door. A woman answers, and he asks her how many children she has and how old they are. She says I will give you a hint. If you multiply the 3 children's ages, you get 36. He says this is not enough information. So she gives a him 2nd hint. If you add up the children's ages, the sum is the number on the house next door. He goes next door and looks at the house number and says this is still not enough information. So she says she'll give him one last hint which is that her oldest of the 3 plays piano.
Want a hint?
Answer to Riddle
Other Good Riddles
  • Zeno's paradox of Achilles and the Tortoise
      Quick summary of riddle: Zeno of Elea (490-425 BC) is known for creating many paradoxes which were debated by mathematicians for centuries. His riddle involving Achilles, the character from Homer's Iliad and a tortoise went something like:
      The tortoise challenged Achilles to a race and Achilles, full of typical hubris, accepted and even gave the Tortoise a 10 foot head start. Before the race started, the tortoise told Achilles that the reason Achilles would lose is that even though Achilles would be catching up, the tortoise would always be moving ahead. Therefore, Achilles would always be covering a fraction of the distance between the two. Let's say he covered half of the distance in 1 second (5 feet) and then in the next he covered half of the new distance, the remaining 5 feet plus the Tortoise's new distance. In the end, the tortoise convinced Achilles that he could not win the race because although he would be getting closer and closer, he would still always be covering smaller and smaller fractions of the total distance between the two. Therefore, Achilles forfeited the race. To read this riddle in a modern narrative form click here.