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Can You Solve The Seemingly Impossible Cyclist And Motorcycles Riddle?

I received this puzzle by email, which I have edited for presentation. I follow your YouTube channel and you are great. I have created a puzzle you might like. A cyclist ascends a long climb at a constant speed of 18 kilometers per hour (km/h). A motorcycle rally starts 1 minute after the cyclist. Every … Continue reading Can You Solve The Seemingly Impossible Cyclist And Motorcycles Riddle? Read more ›

How Many Holes Does A Straw Have? The Correct Answer Explained Mathematically

How many holes does a straw have? This question has generated a lot of debate online. Recently BuzzFeed made a video that already has over 450,000 views. It’s amazing to see topology go viral like this! Topology is a branch of mathematics dealing with the study of shapes and spaces. And it was an important … Continue reading How Many Holes Does A Straw Have? The Correct Answer Explained Mathematically Read more ›

Presidents’ Day Special: Math Homework From George Washington And Abraham Lincoln

For Presidents’ Day, we celebrate the birthdays of George Washington (February 22, 1732) and Abraham Lincoln (February 12, 1809). Both men understood the value of mathematics. Abraham Lincoln studied Euclid’s Elements to understand logical proof (details here). And here’s a quote from George Washington. “Without arithmetic, the common affairs of life are not to be … Continue reading Presidents’ Day Special: Math Homework From George Washington And Abraham Lincoln Read more ›

Another Singapore Birthday Math Problem Stumps The Internet

This is not about the famous Cheryl’s birthday problem. According to Mothership, a Singapore math question on students’ birthday months has everyone stumped. Again. What is the question? It looks easy enough. “There are 37 students in a class. How many students, at the least, are born in the same month?” Okay, so I know … Continue reading Another Singapore Birthday Math Problem Stumps The Internet Read more ›

Can You Solve Abraham Lincoln’s Math Homework?

In honor of Abraham Lincoln’s birthday on February 12, I want to share a fascinating but lesser known story. While Lincoln was studying law, he frequently came upon the word “demonstrate.” He wondered what “demonstrate” meant compared to any other proof. So he looked it up in Webster’s Dictionary and found that demonstrate meant a … Continue reading Can You Solve Abraham Lincoln’s Math Homework? Read more ›

The REAL Answer To The Viral Chinese Math Problem “How Old Is The Captain?” Stumping The Internet

A 5th grade math exam in China had the following question (translated to English): “If a ship had 26 sheep and 10 goats onboard, how old is the ship’s captain?” The question baffled students and parents, garnering headlines around the world. Even I covered the problem, but there is more to the story than anyone … Continue reading The REAL Answer To The Viral Chinese Math Problem “How Old Is The Captain?” Stumping The Internet Read more ›

Two Math Problems “Stumping The Internet” Right Now – China Captain’s Age And The Dog Show

Problem 1: (5th graders in China) “If a ship had 26 sheep and 10 goats onboard, how old is the ship’s captain?” Problem 2: (2nd graders in US) “There are 49 dogs signed up to compete in the dog show. There are 36 more small dogs than large dogs signed up to compete. How many … Continue reading Two Math Problems “Stumping The Internet” Right Now – China Captain’s Age And The Dog Show Read more ›

Hard Geometry Problem With Unbelievably Elegant Solution

I received this puzzle by email. This problem is so up your alley and I am requesting a video on it. Take any equilateral triangle and pick a random point inside the triangle. Draw from each vertex a line to the random point. Two of the three angles at the random point are known, let’s … Continue reading Hard Geometry Problem With Unbelievably Elegant Solution Read more ›

Why Did Facebook Invent A New Unit Of Time? The Flick Explained With Math

On January 22, 2018, Facebook Open Source tweeted, “We’ve launched Flicks, a unit of time, slightly larger than a nanosecond that exactly subdivides media frame rates and sampling frequencies. https://github.com/OculusVR/Flicks.” The story caught my eye, particularly because it is a good example of applying number theory to solve a technical problem! And it’s an easy … Continue reading Why Did Facebook Invent A New Unit Of Time? The Flick Explained With Math Read more ›

Can You Solve The Fibbing Fisherman Riddle?

Thanks to Halvor Kjærås for creating this problem and sending me its solution! Catherine asks, “How many fish did you catch?” Barney says, “I caught 5.” Alfred says, “I caught 2.” Barney then says, “Don’t listen to Alfred. You have to multiply any number he speaks aloud by 6 to get the real value.” Alfred … Continue reading Can You Solve The Fibbing Fisherman Riddle? Read more ›

Can You Solve A×B×C = ABC÷5? A Puzzle From Work

I received today’s puzzle by email, which I have slightly edited for presentation purposes: Hey Presh, Greetings from Norway, I am a big fan of your videos! I got the following fun quiz at work the other day and translated it into English for your thoughts. Tim is playing a Scrabble-like board game with numbers. … Continue reading Can You Solve A×B×C = ABC÷5? A Puzzle From Work Read more ›

Tricky Apple Tree Probability Problem From The Online Math Olympiad

I was suggested this problem by Arbitrary Renaissance who credits the Online Math Olympiad (OMO). The OMO is a contest for high school students. Teams of up to 4 have 11 days to answer 30 questions. Only basic 4 function calculators are allowed. The 2016 Fall test had an average of 9 out of 30 … Continue reading Tricky Apple Tree Probability Problem From The Online Math Olympiad Read more ›

A Very Special Number Puzzle

Here is an edited version of an email I received: Hi, I’m Chunie, a senior high school student in the Philippines (grade 11), big fan of yours on YouTube. Can you please solve this? I’m curious about the smallest number for which all numbers 1 to 100 are factors of that number. I assume it … Continue reading A Very Special Number Puzzle Read more ›

Can You Solve A Maths Exam Problem From Malaysia? The Cylinder On The Wall Puzzle

I received an email with an interesting problem from the Malaysian national exam, which I have adapted for this puzzle. A cylindrical container with length 20 cm is placed on the floor against the wall as shown in the diagram. Point Q is on the edge of the base and Q is 2 cm from … Continue reading Can You Solve A Maths Exam Problem From Malaysia? The Cylinder On The Wall Puzzle Read more ›

I Will Guess Your Age And Shoe Size (2018)

A couple of years ago this math trick got circulated and even got coverage in places like The Telegraph. I wanted to share this trick and explain why it works. I Will Guess Your Age And Shoe Size (2018) Text instructions Follow the directions carefully, and do the calculations in sequence. Use a calculator to … Continue reading I Will Guess Your Age And Shoe Size (2018) Read more ›

Inscribed Circle And Square Puzzle

If the red area (between a square and its inscribed circle) equals the blue area (between a smaller circle and its inscribed square), what is the value of: (large circle’s radius)/(small circle’s radius) Watch the video for a solution. Inscribed Circle and Square Puzzle Or keep reading. Thanks to Yossi Rozhenko for suggesting a problem … Continue reading Inscribed Circle And Square Puzzle Read more ›

Puzzle – If AAA + BBB + CCC = BAAC, What Are A, B, And C?

I received this problem from the following email. “Hello Presh, I presented one of your math questions to my maths teacher and he couldn’t solve it, haha! [Note from me: thanks for sharing my video! So many math teachers follow MindYourDecisions videos it is just amazing. But it’s no big deal if your teacher couldn’t … Continue reading Puzzle – If AAA + BBB + CCC = BAAC, What Are A, B, And C? Read more ›

Tiny But Not So Simple Geometry Problem: Areas From Quadrilateral Diagonals

Thanks to Gerrit for sending me this fun problem along with a solution! A convex quadrilateral is divided into four parts by its diagonals. Three of the areas are 2, 1, and 3 as shown in the diagram. What is the area of the fourth region denoted by x? Watch the video for a solution. … Continue reading Tiny But Not So Simple Geometry Problem: Areas From Quadrilateral Diagonals Read more ›