# Category Soon

Christian Huygens was a Dutch mathematician, physicist and astronomer, born in The Hague, The Netherlands, on April 14, 1629. He was the second of four children of the poet and diplomat Constantijn Huygens (1596-1687). He was a man of wide culture who also devoted himself to the sciences. From his father, Huygens received his first instruction in mathematics and mechanics at the age of thirteen, and from early on aroused interest and skill in both.

Complete the Sequence Difficulty Level: Complete the Sequence: 0, 5, 8, 17, 24, 37, ___ Challenge 136 Empty Squares Product Challenge Index Next >> Challenge 138 Five-digit Number
Half Thirteen Difficulty Level: How can half THIRTEEN be EIGHT? Challenge 114 Eight Queens on the Chessboard Challenge Index Next >> Challenge 116 Digging a Hole
Upside down Difficulty level: Calculate the value of x knowing that if you turn it upside down, its value increases by 50%. Challenge 147 Which number is missing? Challenge Index Next >> Challenge 149 Zoo Logic
The next word Difficulty level: The following word sequence follows a certain rule: T-shirt, acetone, monkey, pineapple, magic What is the next word in the sequence? a) horse b) olive oil c) mayonnaise d) publication e) basketball Challenge 139 Olive in the Cup Challenge Index Next >> Challenge 141 Adroaldson's Wallet
Adroaldson's Wallet Level of difficulty: Adroaldson lost his wallet and went to the police station to report the incident. Arriving there, a police officer told him that a wallet was found and asked Adroaldson to report the contents of his wallet. Adroaldson said he had \$ 63.00 in six notes and none of them was \$ 1.00.
The Fly and the Cyclist Difficulty Level: Two cyclists, in opposite directions, approached on a straight road, pedaling at 20km / h. When 40km away, a fly lands on one of the bikes, then flies to another. Then the fly keeps coming and going between the two bikes, flying at 30km / h, until the cyclists meet.
A special symbol Difficulty level: The symbol represents a special operation with numbers. Here are some examples: 2 4 = 10 3 8 = 27 4 27 = 112 5 1 = 10 How much is 4 (8 7) worth? Challenge 157 Multiple of 9 Challenge Index Next >> Challenge 159 Little John Waiting for Bus
The Flood and the Jealous Husbands Difficulty Level: After a flood, three couples were surrounded by water and were forced to flee their hotel on a boat that could hold no more than three people at a time. Each husband was so jealous that he would not allow his wife to stay in the boat, or anywhere, with any other man (or men) unless he himself was present.
Handshaking Difficulty Level: At the end of a meeting, everyone in attendance shook hands. Edigleidson, who was present, said there were 66 handshakes. How many people attended this meeting? Challenge 161 As many challenges as possible Challenge Index Next >> Challenge 163 The Cat, the Coffee, and the Cake
Fourth power plus four Difficulty Level: Since n is a natural number, when is n 4 + 4 prime? Challenge 188 Climbing the stairs Challenge index Next >> Challenge 190 Boy, girl and dog
The Beggar and the Cigarettes Difficulty Level: Math Only Warns: Smoking is Harmful to Health! A beggar can make one cigarette every 6 cigarette butts he finds. After a full day roaming the streets and checking public ashtrays, the beggar found 72 cigarette butts. How many cigarettes can he smoke?
Root greater than number Difficulty level: Find a number that has a square root larger than itself. Challenge 19 Form the number 24 Challenge table Next >> Challenge 21 Maria and Manuel
Painting the faces of a cube Difficulty Level: A cube has each of its faces painted white or gray. For example: How many different cubes can be made? Challenge 183 Painting Numbers on Cubes Challenge Index Next >> Challenge 185 The World of Cubes
Throwing Dice Difficulty Level: You have two normal six-sided dice, numbered 1 through 6. When you roll them, the total was 5. You will be the winner if you make another 5 before making a 7, otherwise you loses. If it is any other combination before a 5 or a 7, you roll the dice again.
Diophantus' Puzzle Level of Difficulty: History has kept little data about Diophantus. All that is known about him is found in the following epigram on his grave and written in the form of a mathematical riddle: Walker! Here are buried the remains of Diophantus. And the numbers can show (miracle!
How many nines? Difficulty Level: How many nines are there between 0 and 100? Challenge 33 How to cross the river? Challenge Index Next >> Challenge 35 The Price of the Gift
Put the soldiers in rows Difficulty Level: You have 10 soldiers. Form 5 rows with 4 soldiers in each. Challenge 23 How many pages does the book have? Challenges Index Next >> Challenge 25 Number that makes the equation true
All without debt Difficulty Level: A traveler arrives in a country town and enters a small hotel. At the reception, she delivers \$ 100.00 and asks to see a room. While the traveler inspects the rooms, the hotel manager runs off with the \$ 100 bill and goes to the butcher's shop to pay his debt.
Ice Cream Promotion Difficulty Level: One summer, an ice cream factory held a promotion that included exchanging ten ice cream sticks for a stick ice cream. In this promotion, an ice cream stick corresponds to what fraction of the price of an ice cream? Challenge 142 Discover the King's Name Challenge Index Next >> Challenge 144 The Five Apples
Spinning the Coin Difficulty Level: There is an old challenge in which we have one coin standing and one spinning around it. It turned out that the coin (spinning) can make two full turns around the other, which is standing still. Now try to find out: how many full spins will one coin make around three fixed coins in a row?