Three Rivers Riddle
There are three rivers and after each river lies a grave. A man wants to leave the same number of flowers at each grave and be left with none at the end. However, each time he passes through a river, the number of flowers he has doubles. How many flowers does he have to start with so that he is left with none at the end? And how many does he leave at each grave?
Hint:
This problem has an infinite number of solutions modeled by the equation 8a=7n, where a is the amount of flowers the man starts with and n is the number of flowers he leaves at each grave. The simplest and possibly trivial solution would be to start with 0 flowers and leave 0 flowers at each grave. A more significant solution would be to start with 7 flowers and leave 8 at each grave. Any positive integer multiple of this solution also satisfies the conditions. For example, the man starts with 14 flowers and leaves 16 at each grave; so, 14 doubles to 28, and 28-16= 12; 12 doubles to 24, and 24-16= 8; 8 doubles to 16, and 16-16= 0. The result is the same if the man starts with 21 flowers and leaves 24 flowers at each grave, or starts with 28 and leaves 32. Did you answer this riddle correctly?
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YES NO
Crying Wolf Riddle
Hint:
A Special Integer Riddle
A special integer exists in mathematics that shows a special property. If you subtract any number from that integer, the result will always be divisible by the successor of that number completely.
Do you know what that integer is ?
Do you know what that integer is ?
Hint:
The required integer is -1.
For an example, let us subtract 7 from -1.
-1 - 7 = -8
Now the successor of 7 is 8 and (-8) is exactly divisible by 8.
You can try that for any number and it will hold true. Did you answer this riddle correctly?
YES NO
For an example, let us subtract 7 from -1.
-1 - 7 = -8
Now the successor of 7 is 8 and (-8) is exactly divisible by 8.
You can try that for any number and it will hold true. Did you answer this riddle correctly?
YES NO
10 Boxes Riddle
There are ten boxes containing some balls. Each of the ball weighs exactly 10 grams. One of those boxes have defective balls (all the defective balls weigh 9 grams each).
An electronic weighing machine is provided to you and you are allowed only one chance of weighing on it.
How will you find out which box has defective balls ?
An electronic weighing machine is provided to you and you are allowed only one chance of weighing on it.
How will you find out which box has defective balls ?
Hint:
Let us simplify boxes by naming them from 1 to 10.
Now the trick here is to pick different number of balls from different boxes. So to simplify things, we will pick balls corresponding to box number.
Thus, pick 1 ball from Box 1, 2 balls from box 2, 3 balls from box 3 and so on. You will have 55 balls altogether. Now, put them all in the balance.
If all balls were weighing accurate 10 grams, the total weight of the 55 balls would have been 550 grams. But one of the box must have had the defective balls.
Suppose if the defective balls were in box number 2, then the total weight will be 2 grams less than 550. If the defective balls were in box 8, the total weight will be less than 8 grams from 550. In this way, you will be able to identify which box has the defective balls. Did you answer this riddle correctly?
YES NO
Now the trick here is to pick different number of balls from different boxes. So to simplify things, we will pick balls corresponding to box number.
Thus, pick 1 ball from Box 1, 2 balls from box 2, 3 balls from box 3 and so on. You will have 55 balls altogether. Now, put them all in the balance.
If all balls were weighing accurate 10 grams, the total weight of the 55 balls would have been 550 grams. But one of the box must have had the defective balls.
Suppose if the defective balls were in box number 2, then the total weight will be 2 grams less than 550. If the defective balls were in box 8, the total weight will be less than 8 grams from 550. In this way, you will be able to identify which box has the defective balls. Did you answer this riddle correctly?
YES NO
Malcolm's Age Riddle
Malcolm is the number of weeks of his fathers age treated as days and his grandfathers age in months. All three of their ages add up to 120 years. How old is Malcolm, his father and his grandfather?
Hint:
Malcolm is 6.
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years. Did you answer this riddle correctly?
YES NO
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years. Did you answer this riddle correctly?
YES NO
Little Johnny's Cats Riddle
Little Johnny's teacher asks him, "If I gave you two cats, then two more, and two more cats; how many would you have?"
Little Johnny replies, "Seven!"
His teacher asks him again more slowly, "If I gave you two cats, then two more, and two more cats; how many would you have?"
But again Little Johnny replies, "Seven!"
Next she asks, "If I get two cats, then two more, and two more cats; how many would I have?"
Little Johnny replies, "Six!"
"Good Job Johnny! Now if I gave you two cats, then two more, and two more cats; how many would you have?"
Johnny thinks for a second, "Seven."
But Johnny is not wrong. Why?
Little Johnny replies, "Seven!"
His teacher asks him again more slowly, "If I gave you two cats, then two more, and two more cats; how many would you have?"
But again Little Johnny replies, "Seven!"
Next she asks, "If I get two cats, then two more, and two more cats; how many would I have?"
Little Johnny replies, "Six!"
"Good Job Johnny! Now if I gave you two cats, then two more, and two more cats; how many would you have?"
Johnny thinks for a second, "Seven."
But Johnny is not wrong. Why?
Hint:
Grown Men Crying Riddle
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Drying Crying Tears Riddle
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Crying Cookie Riddle
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Green Grass Door Riddle
If you go into the green glass door, you can bring a ball, but not a bat. You can bring a book, but you can't bring a magazine. You can bring coffee, but not a cup. You can bring letters, but you can't bring numbers. Why can you only bring certain things?
Hint: Look at the spelling of the words.
Whatever you bring has to be spelled with double letters. Did you answer this riddle correctly?
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YES NO
Math Wiz Angel Riddle
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Equals Eight Riddle
Hint:
Mirror one of the threes and put it and the other three together to get an eight. Did you answer this riddle correctly?
YES NO
YES NO
The Sad Math Book
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Late Home Work Riddle
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Angry Science Teacher
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