Here are some of my favorite puzzles to challenge students for a few minutes in class. I put these on overhead transparencies and then just pull them out and put them on the overhead!
Mr. Price has the same number of brothers as he has sisters, but his sister has twice as many brothers as she has sisters. How many children are in the family?
A man was carrying a fox, a duck, and a bag of grain to the fair. When he came to a river, there was a canoe on the bank, but it was only big enough to carry two objects at a time. How can the man get all three to the other side without any problems?
Three missionaries and three cannibals arrive at a river together. There is one canoe that holds only two people. If there are ever more cannibals than missionaries in any group, the cannibals will eat the missionaries. How can all six people cross the river without anybody getting eaten?
Which two integers, neither of which contains a zero, can be multiplied together to get one billion? (1,000,000,000)
You have 1,000 in one-dollar bills and 10 empty sacks. How can you distribute the bills among the sacks so that you can provide any whole number of dollars from $1 to $1,000 merely by combining sacks? Each sack must contain at least one bill.
What would give you the most orange juice: Three oranges with one-inch diameters or one orange with a three-inch diameter? (NOTE: V=4/3 * PI * R^3)
There are three errers in this problem. You must detect all of them to to receive full credit.
What is it that occurs once in a second, once in a month, once a century, yet not all in a week or a year?
A caterpillar is at the bottom of a thirty-foot well. Each day she climbs three feet but at night she slips back two feet. On what day will the caterpillar finally make it out of the well?
If it takes 12 minutes to cut a board into 4 pieces, how long would it take to cut a board into 10 pieces?
A quarter-mile of railroad track is staked securely at both ends. If the temperature gets above 100 degrees the rails will expand. If it's hot enough to expand the rails just 2 inches in length, how high off the ground will the rail section buckle (in the middle)?
A certain cube has each side being 10 cm. If you wanted a cube that was twice as big, how long would each side have to be?
There are eight weights, all the same size, shape, and color. They all weigh the same except for one, which is heavier than the rest. Using a balance scale, how can you find the heavier weight in only two weighings?
In the song, "The Twelve Days of Christmas", how many gifts
are given (in total) after the song is completed?
and … suppose you had to take all the presents back …. and you
could only take one present back per day ….
How many days would it take to return all the presents?
If a man-and-a-half can eat a pie-in-a-half in a minute-and-a-half, how many men would it take to eat 60 pies in 30 minutes?
If it cost five cents to break a link, and ten cents to weld it again, what is the least it would cost to join in a single length of chain five sections of three lengths each?
Looking for a pattern: 1 + 2 = 3
4 + 5 + 6 = 7 + 8
9 + 10 + 11 + 12 = 13 + 14 + 15
16 + 17 + 18 + 19 + 20 = 21 + 22 + 23 + 24
What numbers would be in the 50th row?
A man walked 10 km south, then 10 km north. After all this, he still ended up in the place where he began. Where was he when he started?
A farmer raises only cows and chickens. One day she saw all of them loose in the barnyard, and counted a total of 48 legs. If the farmer has a total of 20 animal, how many cows does she have? How many chickens?
How can you cut a two-layer, round cake into eight equal pieces using only three cuts?
If 2 miles of fence encloses 80 acres, how much would 4 miles of fence enclose?
You can receive ten free trees if you can plant them in five rows with four trees per row. Can you accomplish this?
A person 6-feet tall will walk all the say around the equator of the earth. How much farther will their head travel then their feet?
How many squares (of any size) are there in all in a 5 by 5 checkerboard?
A large rope is tied snugly around the equator, a total length of approximately 22,000 miles. If the rope is cut and a 3-foot section is added, how far off the ground (uniform distance all the way around the earth) would the rope now be?
A bus load of girls and a bus load of boys were going to a track meet. At an intersection, 10 boys snuck onto the girls' bus. A few miles later, the bus driver sent 10 people from the girls' bus back to the boys' bus. Are there now more boys on the girls' bus or more girls on the boys' bus?
The minute hand of the clock is missing, but the hour hand is on the eleven minute mark. What time was it when the clock broke?
A woman went into a hardware store to get a few items. She bought 1 for $0.95, 21 for $1.85, and 921 for $2.50. What was the woman buying?
You have a glass of water and a glass of wine. If you take a spoonful of wine and put it into the glass of water, then take a spoonful from the water and put it back into the glass of wine. Will you have more water in the wine glass or more wine in the water glass?
A square castle is surrounded by a square moat whose width is 10 yards. A knight is attempting to cross the moat, but only has two nine-and-a-half yard planks, and no way to fasten them together. How can the knight bridge the moat?
Timothy observes the hour and minute hands of a clock during a period of 24 hours. How many times are the hands at right angles?
A box was made with dimensions 1 foot by 1 foot. When filled to the top with a certain kind of rock, the amount of rock weighed 100 pounds. The owner of the business thought that was too much weight, so she decided to make a smaller box to hold only 75 pounds of rock. What would be the dimensions of a box to satisfy the owner?
Tennis balls are packed tightly, with 3 in every can. Is the can taller than the distance around it or is the reverse true?
A large cube is completely painted on the outside faces. Cut apart the big cube into the smaller cubes shown. How many cubes will have: 3 faces painted? 2 faces painted? only 1 face painted? no faces painted?