5 Math Riddles

  1. A car's odometer shows 72927 miles, a palindromic number. What are the minimum miles you would need to travel to form another?
  2. Why are 1990 dollar bills worth more than 1989 dollar bills?
  3. Robert and David were preparing to have a water balloon fight. "No Fair" cried Robert, "You have 3 times as many as I do!" David said "Fine!" and gave Robert 10 more balloons. "Still not fair!" argued Robert, "You still have twice as many as I do." How many more balloons must David give Robert for them to have the same number?
  4. In a certain city, 5% of all the persons in town have unlisted phone numbers. If you select 100 names at random from that city's phone directory, how many people selected will have unlisted phone numbers?
  5. A man is walking down a road with a basket of eggs. As he is walking he meets someone who buys one-half of his eggs plus one-half of an egg. He walks a little further and meets another person who buys one-half of his eggs plus one-half of an egg. After proceeding further he meets another person who buys one-half of his eggs plus one half an egg. At this point he has sold all of his eggs, and he never broke an egg. How many eggs did the man have to start with?

Answers: 5 math riddles Quiz

  1. 110 miles. (73037)
  2. The same reason seven dollars is more than six. Because there is one more.
  3. David must give Robert another 20 water balloons, giving them each 60. Robert started with 30 water balloons and David with 90.
  4. None. If their names are in the phone directory, they do not have unlisted phone numbers!
  5. 7 eggs. The first person bought one half of his eggs plus one half an egg (3 1/2 + 1/2 = 4 eggs) This left him 3 eggs. The second person bought one-half of his eggs plus one half an egg, (1 1/2 + 1/2 = 2 eggs) leaving the man 1 egg. The last person bought one-half of his eggs plus one-half an egg, (1/2 + 1/2 = 1 egg) leaving no eggs.
  1. 110 miles. (73037)
  2. The same reason seven dollars is more than six. Because there is one more.
  3. David must give Robert another 20 water balloons, giving them each 60. Robert started with 30 water balloons and David with 90.
  4. None. If their names are in the phone directory, they do not have unlisted phone numbers!
  5. 7 eggs. The first person bought one half of his eggs plus one half an egg (3 1/2 + 1/2 = 4 eggs) This left him 3 eggs. The second person bought one-half of his eggs plus one half an egg, (1 1/2 + 1/2 = 2 eggs) leaving the man 1 egg. The last person bought one-half of his eggs plus one-half an egg, (1/2 + 1/2 = 1 egg) leaving no eggs.