Hi students, Welcome to **Amans Maths Blogs (AMBIPi)**. Are you looking for * Brain Teasers for Adult Questions 1 to 20 with Answer AMBIPi* for brain exercise? In this article, you will get challenging math riddles with answers. Solving these tricky math puzzles are brain exercise and you can do solve these in anytime as you wish.

**Hard Math Riddles 1**: Rich Mr. Vanderford buys a bottle of very old French brandy in a liquor store. The price is $45. When the store owner hands him the wrapped bottle he asks Mr. Vanderford to do him a favor. He would like to have the old bottle back to put on display in his window, and he would be willing to pay for the empty bottle. “How much?” asks Mr. Vanderford. “Well,” the store owner answers, “the full bottle costs $45 and the brandy costs $40 more than the empty bottle. Therefore, the empty bottle is .. .” “Five dollars,” interrupts Mr. Vanderford, who, having made a lot of money, thinks he knows his figures better than anybody else. “Sorry, sir, you can’t figure,” says the liquor dealer and he was right. Why?

**Show/Hide Answer Key**

**Answer: 2.50**

Explanation: The empty bottle costs $2.50, the wine $42.50, that is, $40 more than the bottle. If you prefer an equation: b + (b + 40) = 45; b = 2.50.

**Hard Math Puzzles 2**: Two golfers were discussing what might have been after they had played a par 5.

Harry said ‘if I had taken one shot less and you had taken one shot more, we would have shared the hole’.

Geoff then countered by saying ‘yes, and if I had taken one shot less and you had taken one shot more you would have taken twice as many shots as me’.

How many shots did each take?

**Show/Hide Answer Key**

**Answer: Harry 7, Geoff 5.**

Explanation:

**Math Riddles Hard 3**: A used-car dealer complains to his friend that today has been a bad day. He has sold two cars, he tells his friend, for $750 each. One of the sales yielded him a 25 per cent profit. On the other one he took a loss of 25 per cent. “What are you worrying about?” asks his friend. “You had no loss whatsoever.”

“On the contrary, a substantial one,” answers the car dealer. Who was right?

**Show/Hide Answer Key**

**Answer: Dealer.**

Explanation: The dealer was right. The car that brought him a 25 per cent profit cost him $600 (because 600 + 25% = 750). The other car on which he lost 25 per cent cost him $1,000 (because 1,000 – 25% = 750). So the dealer paid a total of $1,600 for two cars which he sold

for $1,500, causing him a loss of $100.

**Hard Math Brain Teasers 4**: A number between 1 and 50 meets the following criteria:

- It is divisible by 3.
- When the digits are added together the total is between 4 and 8.
- It is an odd number.
- When the digits are multiplied together the total is between 4 and 8.

What is the number?

**Show/Hide Answer Key**

**Answer: 15.**

Explanation:

**Math Riddles Hard 5**: In a Tennessee mountain community the miller retains as his fee one-tenth of the corn the mountaineer farmers deliver for grinding. How much corn must a farmer deliver to get 100 pounds of cornmeal back, provided there is no loss?

**Show/Hide Answer Key**

**Answer: 111 1/9 pounds.**

Explanation: (111.111… – 10% = 100)

**Hard Brain Teasers 6**: On arriving at the party the six guests all say ‘Hello’ to each other once. On leaving the party the six guests all shake hands with each other once. How many handshakes is that in total, and how many ‘Hello’s?

**Show/Hide Answer Key**

**Answer: 15 handshakes and 30 ‘Hello’s.**

Explanation: Handshakes: 1-2, 1-3, 1-4, 1-5, 1-6, 2-3, 2-4, 2-5, 2-6, 3-4, 3-5, 3-6, 4-5, 4-6, 5-6 = 15 or 5 + 4 + 3 + 2 + 1. The number of ‘Hello’s is twice as many.

**Hard Math Riddles for Adults 7**: Charley and Sam were to meet at the railroad station to make the 8 o’clock train. Charley thinks his watch is 25 minutes fast, while in fact it is 10 minutes slow. Sam thinks his watch is 10 minutes slow, while in reality is has gained 5 minutes. Now what is going to happen if both, relying on their timepieces, try to be at the station 5 minutes before the train leaves?

**Show/Hide Answer Key**

**Answer: **

Explanation: Charley thinks he will be in plenty of time when his watch shows 8:20, while in fact it is already 8:30, much too late to make

the train. Sam, on the other hand, will reach the station when his watch shows 7:45, which means that he will be there at 7:40, or fifteen minutes too early.

**Hard Maths Puzzles 8**: What two numbers multiplied together equal 13?

**Show/Hide Answer Key**

**Answer: 1 and 13.**

Explanation:

**Math Puzzles Hard 9**: A boy says, “I have as many brothers as sisters.” His sister says, “I have twice as many brothers as sisters.” How many brothers and sisters are there in this family?

**Show/Hide Answer Key**

**Answer: Four brothers and three sisters..**

Explanation:

**Hard Math Riddles for School Students 10**: Working at the stable there are a number of lads and lasses looking after the horses. In all there are 22 heads and 72 feet, including all the lads and lasses plus the horses. If all the lads and lasses and all the horses are sound in body and limb, how many humans and how many horses are in the stable?

**Show/Hide Answer Key**

**Answer: 14 horses and 8 stable hands.**

Explanation: 14 × 4 = 56, 8 × 2 = 16, 22 heads 72 feet

**High School Math Puzzles 11**: You may have come across the ancient problem of the snail which, endeavoring to attain a certain height, manages during the day to come somewhat closer to its objective, though at a snail’s pace, while at night, unfortunately, it slips back, though not all the way.

The question, of course, is how long will it take the persevering snail to reach its goal?

The problem seems to have turned up for the first time in an arithmetic textbook written by Christoff Rudolf and published in Nuremberg in 1561.

We may put it this way (without being sure whether we do justice to the snail’s abilities):

A snail is at the bottom of a well 20 yards deep. Every day it climbs 7 yards and every night it slides back 2 yards. In how many days will it be out of the well?

**Show/Hide Answer Key**

**Answer: 4th day.**

Explanation: One may be inclined to figure that since the snail manages to gain 5 yards (7-2, that is) in every 24 hours, it will reach the edge of the well at the end of the fourth day. This, however, is a fallacy and, moreover, an underestimate of the snail’s speed. For it is evident that at the end of the third day, the snail will be 15 yards up. On the fourth day, with a speed of 7 yards, it will reach the rim of the well within five-sevenths of the daylight hours of that day.

**High School Math Brain Teasers 12**: How many boxes measuring 1 m × 1 m × 50 cm can be packed into a container measuring 6 m × 5 m × 4 m?

**Show/Hide Answer Key**

**Answer: 240**

Explanation: 1 × 1 × 0.5 = 0.5 cubic metres

6 × 5 × 4 = 120 cubic metres

120 / 0.5 = 240.

**High School Math Puzzles 13**: A boat is carrying cobblestones on a small lake. The boat capsizes and the cobblestones drop to the bottom of the lake. The boat, being empty, now displaces less water than when fully loaded. The question is: Will the lake’s water level rise or drop because of the cobblestones on its bottom?

**Show/Hide Answer Key**

**Answer: Dealer.**

Explanation: It will drop for the following reason: While still in the boat, the cobblestones displace an amount of water equivalent to their

weight. Immersed, however, they will displace an amount of water equivalent to their volume, which is less, since cobblestones have a

higher specific gravity than water. (Otherwise, they wouldn’t sink to the bottom.)

**High School Math Reasoning 14**: By what fractional part does four-quarters exceed three-quarters?

**Show/Hide Answer Key**

**Answer: **

Explanation: By one-third. Three of anything, if increased by one-third, becomes four.

**Best Math Puzzles for Adults 15**: If we have two gear wheels of the same size, one of which rotates once around the other, which is stationary, how often will the first one turn around its own axle?

**Show/Hide Answer Key**

**Answer: Twice.**

Explanation: It will turn twice because its motion is a composite one, consisting of its own rotation around its center and its rotation around

the stationary gear wheel. Try it out with two coins of the same size.

**Math Brain Teasers for Adults 16**: What weight should be placed on x in order to balance the scale?

**Show/Hide Answer Key**

**Answer: 6.25 kg.**

Explanation:

**Math Riddles for Adults 17**: Stop a minute and try to remember how to find out quickly whether a number is divisible by 3. Now, the question is: Can the number eleven thousand eleven hundred and eleven be divided by 3?

**Show/Hide Answer Key**

**Answer: Yes, it is divisible.**

Explanation: You will get the wrong result if you write this number 11,111. It should be written 12,111, and this number is divisible by 3, because the sum of its digits is divisible by 3.

**Math Puzzles for Adults 18**: My house number is the lowest number on the street that, when divided by 2, 3, 4, 5 or 6, will always leave a remainder of 1. However, when divided by 11 there is no remainder. What is my house number?

**Show/Hide Answer Key**

**Answer: 121**

Explanation:

**Math Brain Teasers for Adults 19**: If 5 cats can catch 5 mice in 5 minutes, how many cats are required to catch 100 mice in 100 minutes?

**Show/Hide Answer Key**

**Answer: 5**

Explanation: Only 5, of course (unless they get tired before the job is done).

**Math Riddles Hard 20**: My brother is less than 70 years old.

The number of his age is equal to five times the sum of its digits. In 9 years time the order of the digits of his age now will be reversed.

How old is my brother now?

**Show/Hide Answer Key**

**Answer: 45**

Explanation: