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    Quite Easily Done

    A weekly homemade series of puzzles, tricks and mathematics from James Grime of Cambridge University.
    enDr J R Grime37 Episodes

    Episodes (37)

    Maths Puzzle: Coins Solution

    Maths Puzzle: Coins Solution
    QED Gold: Originally uploaded 4th February 2011 Take a random pile of coins. If I tell you how many coins are heads and how many coins are tails, can you separate the pile into two piles with the same number of heads in each. And can you do this with your eyes shut? Take the same number of coins as there are heads. Call this pile 1. Then; Total number of coins in pile 1 = Total number of heads In other words, if h1 and t1 are the number of heads and tails in pile 1, and h2 is the number of heads in pile 2, then; h1 + t1 = h1 + h2 Cancel h1 on both sides and you will see that the number of tails in pile 1 will be the same as the number of heads in pile 2. So, if you turn over all coins in pile 1 you will now have the same number of heads in each pile.

    Möbius Strip Hearts (For Valentine's Day)

    Möbius Strip Hearts (For Valentine's Day)
    QED Gold: Originally uploaded 6th February 2011. The Möbius Strip is a strange mathematical shape which is a loop with only one side and one edge. For more information see wikipedia: http://en.wikipedia.org/wiki/Mobius_strip This is not a new idea, and for this and more mathematical valentines ideas see this blog: http://individual.utoronto.ca/sck/vday.html

    QED Code Challenge 2012

    QED Code Challenge 2012
    Send your entries to the Enigma Project http://enigma.maths.org Challenge ends on the 1st of March 2012. And check out NRICH: http://nrich.maths.org (February 2012 is code month) cipher: VA BT LS EG OT XK PB BH CI FV GA YC QG BP UW IH QD OE DI HL CQ YC QG BP EI LZ GA GB IZ PS AZ DQ NI CY UY EA AI UA BF BV OV QA ZS DP QD PG QM PS WL QY DH BD TL VZ PL LW AH GZ BP IM NI KP DZ QU DH FP CI FV RT SB BP BV XO BE BQ PG KO GE IK KO NA OS DG DG DA OX PO GE LZ GA OP FL WU PU UT WF BV IC HF EQ SP NA UX DC BV crib: "EXTRA LARGE FRENCH FRIES"

    Maths Puzzle: Back to Black

    Maths Puzzle: Back to Black
    I have a board that uses the numbers 1 to 90. I fill the board with Othello piece, they are black on one side and white on the other. All the pieces start black side up. First I flip every second number, so 2 becomes white, and 4, 6, 8 and so on. Then I flip every third number, then every fourth number, until finally I flip every 90th number. Which numbers end up black side up and why? Music by Ghostly Dust Machine http://freemusicarchive.org/music/Ghostly_Dust_Machine/Bad_Panda_79/Ode_To_A_Baby_Snowstorm

    Can you crack the combination lock?

    Can you crack the combination lock?
    The sequence 11221 contains all 2-digit combinations using the numbers 1 and 2. Can you find a sequence that contains all the 3-digit combinations using the numbers 1, 2, and 3. What is the shortest such sequence? Can you find a sequence that contains all the 4-digit combinations using the numbers 1, 2, 3, and 4. What is the shortest such sequence? Then, can you break this lock? By which I mean, find the shortest sequence containing all 4-digit combinations using the numbers 0 to 9. The sequence is 10003 digits long (yes I misspoke in the video!)

    Make a Post-it Note Dodecahedron!

    Make a Post-it Note Dodecahedron!
    How to make a Post-it Note Dodecahedron. Fun and beautiful! If you make one yourself send me the photo! Email address in the video. Follow me on Facebook/twitter etc http://singingbanana.com Thanks to Colin Wright who taught this to me. Follow Colin at http://solipsys.co.uk or on Twitter: @colinthemathmo And thanks to Julia Collins for the headache. Follow Julia and Haggis the sheep at http://haggisthesheep.wordpress.com and @haggismaths