What sorcery is this? The slide method of multiplication! #shorts A longer video: https://youtu.be/iZG25uBwU7M Article https://towardsdatascience.com/four-multiplication-methods-you-might-not-have-learned-in-school-fac2211a24b7

# Category Archives: Math

## The Strange Orbit of Earth’s Second Moon (plus The Planets) – Numberphile

Featuring Matt Henderson… Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ More videos with Matt: https://bit.ly/MattHendersonPlaylist Follow his work on Twitter at: https://twitter.com/matthen2 Previous video with Matt (Chaotic Balls): https://youtu.be/6z4qRhpBIyA Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are […]

## The interesting sum of three angles problem!

Three squares are placed in a row. Connect the bottom left corner of each square to the top right corner of the third square, forming angles with measures a, b, c with the horizontal. What is the sum of a, b, and c? Many people requested this problem, and I thank Roberto O. and Cardist […]

## Area of the Q – Numberphile

Johnny Ball is back talking about Hippocrates, Lunes, and a Fancy Q. More links & stuff in full description below ↓↓↓ Johnny Ball’s website: https://johnnyball.co.uk More Johnny on Numberphile: https://bit.ly/Johnny_Ball An earlier Lunes video we did with Barry Mazur: https://www.youtube.com/watch?v=n_FsAwvxBI8 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported […]

## How many numbers can you find?

I had fun with this puzzle! Seen on Twitter https://twitter.com/ssaraceno19/status/1062504179376115712

## Can you solve the sum of cube roots problem?

I had fun solving this one! Special thanks this month to: Mike Robertson, Michael Anvari, Robert Zarnke, Fiona Harper, Kyle, Jamal Jackson. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions From Professor Behrooz Parhami’s Twitter @BehroozParhami Math problem (not really a puzzle): Solve for x. cuberoor(x) + cuberoot(x – 16) = cuberoot(x – 8) pic.twitter.com/yL6rVC0fiG — […]

## Can you solve the circles between rays problem?

Three circles are wedged between two rays that are 60 degrees apart. If the first circle has a radius equal to 1, what is the radius of the third circle? New Scientist Twitter A small, cylindrical barrel with a diameter of 20 cm has been placed against a straight windbreak inclined at 60° to the […]

## The Lightning Algorithm – Numberphile

Matt Henderson is making lightning in mazes. Check out https://www.kiwico.com/Numberphile and get 50% off your first month of any subscription. More links & stuff in full description below ↓↓↓ More videos with Matt soon… Follow his work on Twitter at: https://twitter.com/matthen2 Previous video with Matt (Chaotic Balls): https://youtu.be/6z4qRhpBIyA Maze solving on our sister channel, Computerphile: […]

## Number of solutions to this tricky equation?!

This is one of the hardest algebra problems I’ve seen on Twitter. Problem from Twitter DOES ANYONE KNOW HOW TO SOLVE THIS PROBLEM? I DIDN'T HAD MATHS IN MY 11th and 12th so i have no idea how to solve it even i searched in YouTube too to know about the method but it didn't […]

## Get Off The Earth (a famous & bamboozling problem) – Numberphile

Featuring Ben Sparks… Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Ben Sparks: https://www.bensparks.co.uk More Ben Sparks on Numberphile: http://bit.ly/Sparks_Playlist Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated […]

## Can you solve the triangle stripes problem?

What is the area of the red stripes? 0:00 problem 1:00 similar triangles 3:00 solution References Similar triangles area (Math StackExchange) https://math.stackexchange.com/questions/1588290/similar-triangles-are-to-one-another-in-the-squared-ratio-of-their-correspondi Euclid similar triangles (book of proofs) https://www.bookofproofs.org/branches/ratio-of-areas-of-similar-triangles/#fn194561578060cbf2cfd1d1e Euclid similar triangles (Clark University) https://mathcs.clarku.edu/~djoyce/java/elements/bookVI/propVI19.html Triangle problem on Scholr https://www.scholr.com/community/question/this-triangle-is-divided-into-nine-paral/258271/ Triangle problem on Quora https://www.quora.com/A-triangle-is-divided-into-nine-stripes-of-equal-height-each-parallel-to-the-same-side-of-the-triangle-The-shaded-stripes-have-a-total-area-of-135-square-units-What-is-the-area-of-the-triangle-in-square-units Triangle problem on Purple Comet! Math Meet April 2018 (problem […]

## Can You Solve A Very Old Cambridge Exam Question?

This was asked to students in 1801, but it is still a challenging and fun problem to solve to this day! Source See page 5, problem 24 https://archive.org/details/cambridgeproblem00cambuoft/page/4/mode/2up Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from […]

## Mathematics is all about SHORTCUTS – Numberphile

Featuring Marcus du Sautoy from Oxford University. Check his latest book “Thinking Better: The Art of the Shortcut” Links & stuff in full description below ↓↓↓ Marcus’s new book on Amazon here: https://amzn.to/3xrujmS (US) https://amzn.to/3jmBJD1 (UK) Marcus on the Numberphile Podcast: https://youtu.be/PVSkzNOXG1k And a Numberphile video about Gödel’s Incompleteness Theorem: https://youtu.be/O4ndIDcDSGc The Seven Bridges of […]

## Can you solve this tricky interview question? The rectangle in a triangle problem

University entrance exams and job interviews have asked questions similar to this problem. What is the area of the rectangle? What is the minimum area of the large triangle? Special thanks this month to: Jamal Jackson, Mike Robertson, Michael Anvari, Robert Zarnke, Fiona Harper, Kyle. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send […]

## A Problem with Rectangles – Numberphile

Featuring Tom Crawford and an Oxford Admissions Question… Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) Extra footage: https://youtu.be/IGiBTK3EtLs More links & stuff in full description below ↓↓↓ More Tom videos on Numberphile: http://bit.ly/Crawford_Videos Tom on the Numberphile Podcast: https://youtu.be/_HwKGncsGo0 Tom Crawford’s website, with links to his work and other outreach: https://tomrocksmaths.com […]

## Simple math problem divides the internet, again!

What is 2 + 2×4 = ? Many people are having arguments about this problem. It’s time for the order of operations to save the day, again! #shorts BuzzFeed Math Problem Viral on Twitter https://www.buzzfeed.com/kristatorres/math-problem-twitter Claudius on Twitter idek what stresses me out more, the fact that 26% somehow got 13 or the fact that […]

## A test question that stumped many students!

A version of this problem was asked in India. Can you figure it out? Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate […]

## Chaotic Balls (and other animations) – Numberphile

Matt Henderson shows us a few animations he created to depict chaos. More links & stuff in full description below ↓↓↓ More videos with Matt soon… Follow his work on Twitter at: https://twitter.com/matthen2 Chaos with Ben Sparks: https://youtu.be/kbKtFN71Lfs Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science […]

## Solving a tricky sum of square roots (Olympiad practice)

Thanks to Devesh from India for the suggestion! A version of this problem was given in an Olympiad qualifying test. Socratic https://socratic.org/questions/a-root-a-b-root-b-183-a-root-b-b-root-a-182-find-9-5-a-b Math StackExchange https://math.stackexchange.com/questions/2405256/find-the-value-of-frac95ab-given-that-a-sqrtab-sqrtb-183-and-a Brainly https://brainly.in/question/3901575 Quora https://www.quora.com/Suppose-a-b-are-positive-real-numbers-such-that-a%E2%88%9Aa-+-b%E2%88%9Ab-183-a%E2%88%9Ab-+-b%E2%88%9Aa-182-How-do-we-find-9-5-a-+-b Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy […]

## Three Dice Trick – Numberphile

Ben Sparks with another trick – can you guess how it works before he explains it? More links & stuff in full description below ↓↓↓ This is the second of a trilogy of dice tricks with Ben Sparks… More to come… Martin Gardner called this trick “Guessing The Total”. More dice videos from Numberphile: http://bit.ly/Dice_Videos […]

## What Is The Area Of This Infinitely Repeating Shape?

If the first square has a side length equal to 1, what is the sum of all blue areas? Can you solve this fascinating problem? 0:00 Problem 1:11 Hint 3:58 Solution Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If […]

## An epic limit!

Can you solve this incredibly difficult calculus question? I had a lot of fun solving this one! Special thanks this month to: Kyle, Mike Robertson, Michael Anvari. Robert Zarnke, Fiona Harper. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Adapted from Comment from discussion PhysicsHelpBernoulli’s comment from discussion "[12th grade math] What number would n have […]

## Find the area of the middle rectangle

Can you solve this geometry brain teaser? Note: I was emailed a similar problem but I am unable to locate the original source. It seems to be in the style of Bright Side quizzes, but often those are based on problems circulating. Please let me know if can identify the original source and I will […]

## The Volume of a Sphere – Numberphile

Johnny Ball discusses Archimedes and the volume of a sphere. Check out https://www.kiwico.com/Numberphile and get 50% off your first month of any subscription (sponsor) More links & stuff in full description below ↓↓↓ Johnny Ball: https://johnnyball.co.uk More Numberphile videos with Johnny Ball: http://bit.ly/Johnny_Ball Johnny Ball books: https://amzn.to/3v8Xxqx Numberphile is supported by the Mathematical Sciences Research […]

## Length of an elastic band around 3 circles

Can you solve this interesting geometry problem? References Solution by “WAY TO GOVT JOB” on YouTube Stretched length of band https://www.thestudentroom.co.uk/showthread.php?t=1936482 Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a […]

## Hidden Dice Faces – Numberphile

Featuring Ben Sparks. More links & stuff in full description below ↓↓↓ Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) This is the first of a trilogy of dice tricks with Ben Sparks… More to come soon… Martin Gardner called this trick “Hummer’s Die Mystery” and attributed it to Bob Hummer in […]

## A very challenging question about fractions

Can you solve this challenging problem? Thanks to Ramesh for the suggestion! 0:00 Problem 1:18 Method 1 4:11 Method 2 (Sorry about the repost! In the previous video I had m = -1 by mistake around 3:05. I thank Andy Chen for alerting me of the typo! This is the original video: https://youtu.be/w6xul7j4t_U) Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 […]

## The area when two circles square off

Can you solve for the area of the square and the length of the tangent line? Special thanks this month to Fiona Harper, Kyle, Mike Robertson, Michael Anvari, Robert Zarnke. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Adapted from a puzzle by Twitter @Cshearer41 (Catriona Agg) A semicircle and quarter circle inside a square. How […]

## Planing Sequences (Le Rabot) – Numberphile

Featuring Neil Sloane from the OEIS – and his carpenter’s plane. Mandelbrot papers offer: https://www.patreon.com/posts/52011294 More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile The OEIS: https://oeis.org Discuss this video on Brady’s subreddit: https://redd.it/nrba65 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by […]

## A very nice problem from the UK

Students in the UK faced a similar question to this one. Can you figure it out? Adapted from [GCSE Edexcel Further Math] How would you solve for x? from HomeworkHelp Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you […]

## Parabolas and Archimedes – Numberphile

This video features Johnny Ball. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Johnny Ball: https://johnnyball.co.uk More Numberphile videos with Johnny Ball: http://bit.ly/Johnny_Ball Johnny Ball books: https://amzn.to/3v8Xxqx Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by […]

## A Tricky Puzzle Solved In 2 Ways!

I received many requests for this challenging problem. Can you solve it? Thanks to Toli for the suggestion! Geometry solution in method 1 http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/15degreesgeometric.html Another geometry solution http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/solution2.html Trigonometry solution http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/15degreestrigonometric.html Go Geometry discussion https://gogeometry.blogspot.com/2009/11/problem-395-square-15-degree.html https://drive.google.com/file/d/1A0Az5nJ9wGBwcM2F4gQY2dSfeKJZ1gSS/view Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I […]

## Gambling with the Martingale Strategy – Numberphile

Tom Crawford discussing roulette and gambling with a famed strategy. More Tom videos on Numberphile: http://bit.ly/Crawford_Videos More links & stuff in full description below ↓↓↓ Tom Crawford’s website, with links to his work and other outreach: https://tomrocksmaths.com Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, […]

## A fun sum of sums

Can you solve this tricky algebra problem? 0:00 Problem 0:49 Hints 4:12 Solution Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I […]

## A Sequence with a Mistake – Numberphile

Sequence guru Neil Sloane on a sequence which puzzled him – until he spotted the mistake! More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile The OEIS: https://oeis.org Hanny’s Voorwerp: https://youtu.be/RDr6bSB6Vlg Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a […]

## A Mesmerizing Area Puzzle

This problem is adapted from the first round of the 2017 Dutch Maths Olympiad. Special thanks this month to: Robert Zarnke, Marq Short, Kyle, Mike Robertson, Michael Anvari. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Reddit Math Riddles Simple square puzzle from mathriddles Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many […]

## The “Impossible” Ages of Sisters Puzzle

Asha and Lata are two sisters with mathematically interesting ages. If you write Lata’s age after Asha’s, you get a 4 digit perfect square. Amazingly the same thing happens if you repeat the exercise in 11 years. How old are Asha and Lata currently? 0:00 Problem 1:09 Difference of squares 2:25 Solution Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send […]

## The Math of Being a Pig – Numberphile

Featuring Ben Sparks. Check out https://www.kiwico.com/Numberphile and get 50% off your first month of any subscription. More links & stuff in full description below ↓↓↓ Extra footage from the making of this video (including Brady trying to roll 50 points and his game against the online Pig Player): https://youtu.be/zD9-V9Idbug Ben Sparks: https://www.bensparks.co.uk More Ben Sparks […]

## The challenging 7 squares puzzle from Vietnam

Thanks to Thinh for suggesting this problem! What is the area of a single square? A version of this was given to 12-13 year olds in Vietnam. I admit I didn’t see the trick, but it is a fun one! VN Express (in Vietnamese) https://vnexpress.net/bai-toan-cau-kinh-7-o-vuong-4169822.html Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end […]

## A tricky problem with a “divine” answer!

Can you solve this equation? Thanks to Hrigved for the suggestion! Reference https://math.stackexchange.com/questions/438452/find-all-real-numbers-such-that-sqrtx-frac1x-sqrt1-frac1x Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I […]

## Eureka Sequences – Numberphile

OEIS founder Neil Sloane with more sequences to ponder – of course! Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile Visit the OEIS: https://oeis.org/ Today’s featured sequences: https://oeis.org/A008864 and https://oeis.org/A001043 Numberphile is supported by the Mathematical Sciences Research […]

## The angle between rotated squares

Can you solve this fun little geometry puzzle? Thanks to Roman for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate […]

## Can You Solve The Two Boats Puzzle?

Two boats make a round trip from opposite shores of a lake. They meet and pass at 500 units from the left shore, then at 300 units from the right shore. The boats move at a constant speed and turn around instantly from the shores. What is the distance between the shores? What is the […]

## The Levine Sequence – Numberphile

Neil Sloane from the OEIS has another number sequence which escalates quickly. More links & stuff in full description below ↓↓↓ More videos with Neil Sloane: http://bit.ly/Sloane_Numberphile Levine’s sequence on the OEIS: https://oeis.org/A011784 Neil is the founder and keeper of the The On-Line Encyclopedia of Integer Sequences: https://oeis.org/ Numberphile Podcast: https://www.numberphile.com/podcast Unmade Podcast: https://www.unmade.fm/ Numberphile […]

## Only 6% Solved This

This is a fun algebra problem. Can you figure it out? Thanks to Aslah from India for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for […]