**Hardest Math Quiz**

Try to answer these Hardest Math Quiz without looking the answers first… Can you do it?

Maths is a very powerful instrument: it is possible to arrive at high-level results or applications that seemed beyond our reach.

Thanks to math, you will be able to understand the world around you but also better approach other disciplines such as physics, chemistry, economics, etc.

Math is like a game: logical, formal, math stimulates your thinking like logical games like chess, Sudoku and even the famous Candy Crush Saga!

Once you have grasped the main basics, the math becomes a kind of second nature that helps you interpret the problems facing you.

Maths and seduction are often associated! So try your luck with this Hardest Math Quiz.

**6 years ago, my brother was twice my age. In 5 years, we will both be 40 years old. What’s my age ?**

We complicate the math a little bit with a system of two equations and two unknowns. Am I reviving painful memories?

Let Y be my age, and Z the age of my brother.

The first sentence translates to: Z-6=2(Y-6), which simplifies to Z+6=2Y.

The second sentence is written: (Z+5)+(Y+5)=40

Note the little trap, since “in 5 years” counts for both people!

As we are looking for Y (my age), let’s isolate Z in the second equation, i.e. Z=30-Y, which we inject into the first, i.e.: 30-Y+6=2Y.

We pass the -Y to the right, which gives us 36=3Y.

Y=12 years.

And for those who like a well-finished job, Z=30-12. My brother is 18 years old.

**In a group, 70% of people wear a blue sweater, 75% blue pants, 85% a blue hat and 85% a blue coat.**

**What minimum percentage of people wear only blue clothes?**

Answer: 15%. Thinking backwards, we realize that 85% of those present do not have AT LEAST one of the accessories described.

**If you choose an answer to this question at random, what is the probability that it is correct? A) 50% B) 25% C) 60% D) 25%**

Answer: Well 0% actually. If you choose 25%, you have a 50% chance of getting it right; if you choose 50 or 60%, you get 25%.

**To check where the interference is coming from, a flight attendant questions the passengers.**

**“Who has their computer on? Fifteen hands go up.**

**“Who has their phone on? Thirteen hands go up.**

**“Who has the two lit? Seven people show up.**

**“Who doesn’t have a computer or a phone on? Nine people answer. How many passengers are there on the plane?**

Answer: 30. 15-7 + 13-7 + 7 + 9 = 30

**How many 7s are there in a numbered book of 1 to 120 pages?**

Assuming of course that it is not a math book and that the probability that the number 7 appears black on white in the body of the text is zero, huh. Otherwise it’s no game.

Answer: 22. I’ll let you check for yourselves.

**What is the only number whose square of half is equal to its double?**

Answer: 8. Half of 8 is 4 and 4×4 = 2×8 = 16.

**What number flips when you multiply it by 9?**

When we say that it reverses, it is rather that it becomes the symmetrical of itself, not that we put a 1 with a fraction bar above its head.

Answer: 1089; 1089×9 = 9801.

**Which 4 consecutive digits add up to 10? Hint, it’s not 1261, 1262, 1263 and 1264.**

Answer: 1, 2, 3 and 4: if you haven’t found this one, nothing can be done for you.

**You can only use the digits 2 and 7 and the multiplication operation. You must obtain 32. How to do it?**

No, 7×2 is not 32.

Answer: 2x2x2x2 = 32. Why bother with the number 7?

**What is the number to which when we add the same number, its half, its quarter and 1 gives 100?**

Go ahead, I let you test with all the numbers in the world.

Answer: 36 (36+36+18+9+1=100)

**A clock strikes six in 5 seconds. How long does it take this clock to strike at noon?**

Yes, I know that the clocks that strike the hours are terribly 1872, but don’t blame me, huh, it works less well if we’re talking about smartphones.

11 seconds and not 10, because it is necessary to consider the intervals and not the strokes.

**Consider a shelf with books. The middle book is the fifth from left and right. How many books are there?**

Guys go out, read a good book, stop the Internet, finally! 9, quite logically, there are 4 on each side.

**What is my credit card code?**

Yeah, no don’t hack me. I give you info: 1. The sum of its 4 digits is 13.2. The thousands digit is twice as large as the ones digit,3. The hundreds digit is 3 times larger than the tens digit. The answer is 6313. But I won’t give you the security code 😉

**What is half of 2+2?**

She’s easy, that one. Well no, it’s 3 children. You weren’t asked what was half of (2+2) but what was half of 2, +2. That is 1+2. Or 3.

**Is it cheaper to take a friend to the cinema twice, or two friends to the cinema once at the same time?**

Afterwards, if you’re rich, that’s up to you, huh. To invite two friends at the same time. If you invite them in turn, you will have to pay for one more place, yours during the second session.

**And another question, how to calculate duration with speed and distance?**

Since speed is equal to distance divided by time, to determine a time, simply divide the distance traveled by the speed. For example, if John drove at the speed of 45 km per hour and traveled 225 km in total, he rode for 225/45 = 5 hours in total. How to convert 1h30 into minutes? Multiplying the number of hours by 60 will again give you the number of minutes. Technically, you multiply by 60 minutes (1 hour) so that the two “minutes” simplify.

**How to calculate the number of hours worked per day?**

The principle is simple: when working hours are considered as actual working time, they are hours paid by the employer. Thus, to calculate the working time of the employee, it suffices to add up all the hours considered as effective working time.

**9-3: 1/3+1 =?**

Answer: First, you have to be pragmatic and identify operational priorities. Multiplication and division take priority over addition and subtraction (4th grade program). There is therefore no question of calculating additions and subtractions normally (9-3, then 6 – (1/3) = 18 and finally 18+1 = 19) under penalty of failing like the majority of Internet users.

The fraction remains. But how to divide it? In fact, you have to do a “reverse multiplication”. So multiply 3 by the denominator which is also 3. That is (9-3×3+1). Therefore, it suffices to multiply the numerators and the denominators together in order to make the fraction simpler. So (3×3/1), which is equal to 9. So all that remains is to calculate the whole thing: 9-9+1=1. And voila.

**So why can’t we divide by zero?**

For any number x, its inverse is therefore x’ such that x x x’ = 1. However, zero has no inverse since any figure multiplied by zero always gives zero. Therefore, division by zero is impossible and would lead to mathematical misinterpretations. One can also ask how to make 10% of a sum? How to calculate the percentage of a value

To calculate the percentage of a value, multiply the partial value by 100, then divide by the total value. The formula for calculating the percentage of a value is therefore: Percentage (%) = 100 x Partial value/Total value.

**Why can we say that 2036/4 = DIX?**

Answer: because the answer 509 is written in Roman numerals: D=500, IX=9.

A kindergarten teacher asks her pupils to cut strips of 2cm by 10cm. To do this, she gives them a square sheet of 10×10 cm. On average, a child in this class takes 20 seconds to cut a strip. How long will it take on average for a child to completely cut his sheet into strips?

Answer: We might be tempted to say 1mn40 but when there is 4cm*10cm left, only one cut is needed to make 2 strips. The child will therefore take 1 minute and 20 seconds to obtain the 5 strips: (10/2-1)*20 = 80 seconds or 1mn20s

A snail is at the bottom of a 10 meter well. During the day, it rises 3 meters and at night it descends 2 meters. When will he come out of the well?

Answer: 8 days. In 24 hours, it therefore climbs 1 m each day. In fact after 7 days it reaches 7 m, then on the 8th day, it first climbs 3 m (before descending) it has reached the top!

**There are 313 reindeers doing running race. Bobby realizes that he has twice as many reindeers in front of him as behind him. What is Bobby ‘s position in the race?**

Answer: 209.

**Santa Claus leaves for his tour with 6 reindeer. Each reindeer carries 3 sprites on its back and 2 fireflies on its horns. Each elf carries 3 bags that each contain 10 presents. How many living beings go on the round of presents?**

Answer: There are 37 living beings. Each reindeer carries 3 elves and 2 fireflies: 6x(3+2) + 6 + 1. There is therefore: 1 Santa Claus 6 reindeer 18 elves (6×3) 12 fireflies (6×2)

**What number do you get when you multiply all the numbers on a classic telephone keypad?**

Answer: 0 because 0x1x2x3x4x5x6x7x8x9 = 0 (and yes, we must not forget that).

**I am 4 times my son’s age. In 20 years, I will be twice his age. How old are we?**

Answer: I am 40 years old and my son is 10 years old.

**As night falls, an elephant heads for an oasis to quench its thirst. On his way, he meets four tigers who each carry two hyenas on their backs. These carry themselves each on their head four small robins. In total, how many animals will drink at the oasis?**

Answer: Only the elephant is heading towards the oasis. The others come back.

**Matthew enters a club exclusively reserved for men. 600 men are members of this club. Of these, 5% wear an earring. Of the remaining 95%, half wear 2 earrings and the others none. How many earrings do you wear in this club?**

Answer: There are as many ear balls as limbs, i.e. 600. Indeed, 5% or 30 of these men wear 1. Of the remaining 570, i.e. 95%, half wear 2 and one other half none, that is to say that they all wear one.

**89, 106, 113, 118, 128, ? What is the next number in this logical sequence?**

Answer: The solution is 139. To get the next number, add the digits of the previous number and add it to this number. So to get the solution, we do: 1+2+8 = 11 -> 128+11 = 139.

**If three cats catch three mice in three minutes, how many cats does it take to catch a hundred mice in a hundred minutes?**

Answer: If three cats catch three mice in three minutes, it means that these three cats catch one mouse in one minute. So a hundred mice in a hundred minutes.

**There are several books on a shelf. If a book is fifth from the left and fifth from the right, how many books are there on that shelf?**

Answer: There are 4 books on each side of the book so 9 in total.

**John picks up cigarette butts to be able to smoke. With 4 butts, he makes a cigarette. If he picks up 40 cigarette butts, how many cigarettes will he be able to smoke in total?**

Answer: 13. With his 40 butts, he can smoke 10 cigarettes. Those ten smoked cigarettes give him 10 butts again. he can therefore smoke two new cigarettes and keep two butts. Those two extra cigarettes give him two more butts. Associated with the two butts put aside, it gives him a new one. 10+2+1=13.

**Let’s take a group of women. 70% wear a blue sweater, 75% wear blue pants, 85% wear a blue hat, 85% wear a blue coat. What minimum percentage of women wear only blue clothes?**

Answer: 15%. To find the minimum, we reason backwards. 30% don’t have a blue sweater, 25% don’t have blue pants, 15% don’t have a blue hat, and 15% don’t have a blue coat. We add. 30 + 25 + 15 + 15 = 85. So 85% of women are not completely dressed in blue. We deduce that there are at least 15% of women who have a matching outfit.

**What number divided by itself gives its double?**

Answer: 0.5. Any number other than 0 divided by itself is 1.

**If six men dig five holes in five minutes, how long will it take two men to dig half a hole?**

Answer: A half hole does not exist! No matter how small, a hole is still a whole hole.

**A teacher counts his students on the first day of school. He thinks: I’m sure that at least six students were born on the same day of the week, but I’m not sure that there are four who were born in the same month. How many students are there in the class?**

Answer: 36. Assuming that there is an equal distribution in the days of the week, we can obtain 35 pupils (7×5) without there being more than 5 births on the same day of the week . But the teacher (of mathematics no doubt) is sure that at least six of his students were born on the same day. we can therefore deduce that there are strictly more than 35 students in the class. The same reasoning, reversed, for the months allows us to deduce that the number of students is necessarily less than 37.

**The 1st digit is 2 times larger than the 2nd. The sum of the 4 digits makes 14. The 3rd digit is 3 times larger than the 4th. What is the code?**

Answer: The solution is 4262. We know that the 1st digit is twice as large as the 2nd, so there are only 4 possibilities: 2-1-x-x4-2-x-x6-3-x- x8-4-x-x

We also know that the 3rd digit is 3 times greater than the 4th, there are only 3 possibilities: x-x-3-1x-x-6-2x-x-9-3

Finally, we are told that the sum of the 4 digits is 14.

There is then only one possible combination giving 14 from the possibilities found above: 4-2–6-2 (4+2+6+2=14)

**Matthew meets 3 people Emma, Jeanne and Urbain: Emma: “Stephane has more than 100 spiders at home”. Jeanne: “Never! I’m sure he has less than 100”. Urban: “I’m sure he has at least one”! If only one of the statements is true, how many spiders does Stéphane have at home?**

Answer: 0. If Emma’s statement is true then Urban’s is also true, which is impossible since we know that only one statement is true. There remains then Jeanne’s statement, but if it is true then that of Urbain is also true, still impossible.

**Simon and Louise want to go see a show given at the Great Pyramid, 20km away. The show starts in 3 hours. But on foot, at the speed of 5 km/h, they know that they will not arrive in time. They do have a young dromedary, capable of going twice as fast as them, but who can only carry one dromedary at a time. “And yet, there is a way to be on time,” their grandfather told them. ” How ?**

Answer: Simon leaves with the dromedary and Louise leaves at the same time on foot. Simon after 1 hour has traveled 10 km, he has 2 hours left to do the remaining 10, so he is on time. He attaches the dromedary and continues on his way. After 2 hours, Louise will have traveled 10 km and will find the dromedary. He will have 1 hour left to cover the 10 km with the dromedary. Simon and Louise will arrive together and on time for the show.

**The seats of a chairlift are evenly spaced and numbered in order from 1. When place 13 crosses place 25 then seat 46 crosses 112. What is the total number of seats?**

Answer: When seat 13 intersects with 25, 19 is at one end. Meanwhile, seat 46 crosses 112, which means seat 79 is at the other end. To obtain the total number of seats, the following calculation is made: 2 x (79 – 19) = 120. The chairlift has 120 seats.

**Going to the supermarket, you count 20 houses on your right and coming back, 20 houses on your left. How many houses are there?**

Answer: 20 are the same houses.

**If 1 equals 5, 2 equals 25, 3 equals 605, 4 equals 10855, 5 equals what?**

Answer: 5 equals 1.

**Imagine that you have a lot of friends (an infinite number). The first comes to see you and asks you for 1/2 a glass of champagne. The second asks you for 1/4 glass of champagne. The third asks for 1/8 etc… How many glasses of champagne should you plan to satisfy all your friends?**

Answer: A single glass of champagne will suffice. In mathematics, this infinite sequence is equal to 1: 1/2 + 1/4 + 1/8 + 1/16 + … + 1/2^n = 1.

**How to get 24 with the digits 5, 5, 5 and 1, using each digit only once?**

Answer: 1/5 = 0.25.2 = 4.85×4.8 = 24.

Other answer: 1) 5×5-1?2) (?(5 X 5)) X 5 – 1

**There are 24 passengers in a bus. At the first stop, a third of the bus passengers get off, but none get on. At the 2nd stop, half of the remaining passengers get off, and 3 times more (compared to the 1st stop) passengers get on. At the 3rd stop, 7 people get on and 2 get off. Only 3 passengers are standing. Counting only the people seated, how many feet can we count in the coach?**

Answer: 22 feet. 1/3 of 24 equals 8. So 24-8 = 16. There are 16 passengers left. At the 2nd stop, half of the remaining passengers get off, and 3 times more (compared to the 1st stop) passengers get on. There are 16 passengers left. Half go down, there are 8 left. But none go up go up (3 x 0 = 0 ). So there are 8 passengers left on board. At the 3rd stop, 7 people get on and 2 get off. 8 passengers. 7 goes up so there remains 8+7 = 15. But 2 goes down. 15 – 2 = 13. Only 3 passengers are standing. 13 – 3 = 10. Don’t forget the bus driver. 10 x 2 = 20 (number of passenger feet). 20 + 2 = 22 (we add the two feet of the driver).

**Sylvain offers a bet to his neighbour. “I give you 10 euros that if you give me 20 euros, I will give you 30 euros in return.” Is it interesting for the neighbor?**

Answer: No, it is not interesting for the neighbor. There are two possible cases:

1/ Sylvain wins par. The neighbor earns nothing. The neighbor gave 20 euros + 10 euros of the lost bet and he receives 30 euros in return. Null operation.

2/ Sylvain voluntarily loses the bet. The neighbor gave 20 euros but Sylvain does not give him anything in return. Sylvain losing the bet, he must give 10 euros to the neighbor. In the end, the neighbor loses 10 euros (20-10).

**If a water lily doubling its area each year completely covers a pond after 10 years. How long would it have taken for the pond to be completely covered if there had been 2 water lilies with the same properties?**

Answer: Since each water lily doubles in area each year, the water lily which will entirely cover the pond in the 10th year, only covers it by half in the 9th year. The 2nd water lily also, so between them 2, it covered it entirely.

**Quentin wants to paint his room. We know that with one liter of paint, he can paint 8m². He needs three 5 liter buckets of paint to do the two coats in this 2.5m high square room. What is the floor area of the room?**

Answer: 36m². With 3 buckets of paint, i.e. 15l, you can paint 120m² (15×8), so one layer covers 60m². If you divide this surface by the height of the room, you get its perimeter: 60/2.5 = 24. One side is therefore 6m.

**In a pond there are ten fish. Two drowned, four are swimming away and three are dead. How many fish are there left?**

Answer: 10 because they never left the pond.

**An inflated air mattress is placed on the water of a swimming pool. What will raise the water level the most: Throwing a 1 euro coin in the water or throwing a 1 euro coin on the mattress?**

Answer: The water level will rise higher if the coin is thrown on the mattress. In water, the part displaces its volume of water. On the mattress, the part displaces its weight of water. The metal being heavier than water (the part does not float), its weight of water is greater than its volume of water.

**Laurent is the manager of his own hairdressing salon. He does a gentleman’s hair and at the end of the service, asks him for 15 euros. The customer only has a 20 euro note and the manager has no change. Laurent goes to his neighbour, the pharmacist, to exchange the €20 note for a €10 note and two €5 notes. He can thus return the €5 to the customer. Later in the day, the pharmacist comes to see Laurent to tell him that the €20 note is fake. Annoyed, he agrees to give her a €20 note. How much money did Laurent lose in this story?**

Answer: Laurent has lost €20. The pharmacist gave €20 and received €20 (the counterfeit note is in the trash) The customer won €5 and a free cup because he used a counterfeit note but received the €5 for change Didier lost the 5€ given to the customer + the price of the cup which has not been paid (false ticket).

**Max and Astrid are brother and sister. Max says he has as many brothers as sisters. Astrid says she has twice as many brothers as sisters. How many brothers and sisters are there in total?**

Answer: 7. To find the solution, all you had to do was pose the following two equations: (X-1)=Y (we take away 1 because Max is not his own brother) and X=2(Y-1). Otherwise, we could also make a drawing to understand more easily.

**I have four. I take away one. I have five left, why?**

Answer: You have to count in Roman numerals. I have IV, I remove the I, I only have the V symbol left.

**10 black socks, 8 red socks and 6 white socks are mixed up in a drawer. It is dark in the room. How many socks must we extract at the MINIMUM of socks in order to be sure to have two socks of the same color?**

Answer: As there are three different colors, 4 socks will make a complete pair.

**A few minutes before takeoff, a flight attendant notices interference. She then asks the passengers: “Who has their computer on?” Fifteen hands go up. “Who’s got their phone on?” Thirteen hands go up. “Who has the two lit?” Seven people show up. “Who doesn’t have a computer or a phone on?” Nine people answer. How many passengers are there on the plane? (Not including aircrew)**

Answer: There are 30 passengers (excluding the crew of course). We know that 7 people have a computer and a telephone turned on. We deduce that: 8 people have only their computer on (15-7), 6 have only their telephone on (13-7). We also know that 9 people have no device turned on. 7 + 8 + 6 + 9 = 30

**It is the annual shooting competition at the castle and 218 archers are registered. The rule is simple: each archer faces another in a duel, and the loser is eliminated. Whoever remains at the end is crowned champion. How many duels must be played in total?**

Answer: 217. This is the number of archers eliminated, one archer being eliminated in each match. To calculate quickly, it is necessary to reason by the loss and not by the gain.

**A family of 5 goes to the photographer for a photo where they will all appear. To make a good photo, the photographer wants to take a photo by testing all the possible places between the members of the family. How many photos did he take?**

Answer: 120. 5 x 4 x 3 x 2 x 1 = 120.

Sources: PinterPandai

Photo credit: Chenspec / Pixabay (Pixabay License)