Is there a Mathematician in the house?

KeithandMargaret
KeithandMargaret Forum Participant Posts: 660
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edited September 2017 in Fun & Trivia #1

Which number is the odd one out - and why?

6, 22, 40, 51, 57, 77, 81

Comments

  • EasyT
    EasyT Forum Participant Posts: 16,194
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    edited September 2017 #2

    57 because it is a prime number. Only devisable by itself or one to obtain a whole number. 

     

    Ooops. Oh no it isn't must be 81 because it is a square (9x9)

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #3

    40 is an odd one out as it's the only one divisible by 10. No remainder!

    Ten being the key number in the decimal system. Does anyone know why base ten became the dominant base system in our ancient and modern world? I've often wondered that!

  • robsail
    robsail Forum Participant Posts: 1,441
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    edited September 2017 #4

    57 is the odd one out, as part of the brand Heinz for  tomato ketchup!

  • Cornersteady
    Cornersteady Club Member Posts: 14,425 ✭✭✭
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    edited September 2017 #5

    any of (most of) the above but I'll pick 51 as it is the only prime number. 57 looks prime but isn't 3x19=57. If you think it's prime you are in good company, a mathematician with a funny sounding name (who if I wasn't drinking in a lovely pub in Keswick I could probably remember, but its sounds like the creator of the Simpsons, maybe another pint will help?) thought it as well.

    This was a good starter when I was working, if you hadn't prepared anything you could pick some numbers and ask the class for as many odd one outs as you could find, with a bit of luck it could take a while.

    But having said, 51 is too obvious so I think I'll pick 6 as it is the sum of it's proper divisors and so it is the smallest perfect number

    OK, find as many special things as you can for the number 383? 

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #6

    383 - a palindromic number!

  • EasyT
    EasyT Forum Participant Posts: 16,194
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    edited September 2017 #7

    51 is divisible by 17 and by 3 and so is not prime. If the components of a number are divisible by 3 then the number is. So in the case of 51 .... 5 plus 1 equal 6 which is divissable by 3 and hence so is 51

  • moulesy
    moulesy Forum Participant Posts: 9,402 ✭✭✭✭✭
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    edited September 2017 #8

    "I'll pick 51 as it's the only prime number"

     

    Corners- shame on you! Isn't 51 = 3x17? Too much ofsted and not enough classroom I'd say! sealed

     

    Drat, too quick for me, Alan! wink

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #9

    Shouldn't that be classroom our m?wink

  • moulesy
    moulesy Forum Participant Posts: 9,402 ✭✭✭✭✭
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    edited September 2017 #10

    sealed

  • Cornersteady
    Cornersteady Club Member Posts: 14,425 ✭✭✭
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    edited September 2017 #11

    Wow, guilty as charged, wow, this cumberland ale is good.

  • Cornersteady
    Cornersteady Club Member Posts: 14,425 ✭✭✭
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    edited September 2017 #12

    yes,

    and its prime 

    and it's the sum of three other palindromic numbers

    and those three palindromic numbers themselves are prime

    and is the smallest prime that can be represented by the sum of a prime and its reversal: 383 = 241 + 142.

    and it's a Woodhall prime 

    and it's the only know multi digit Woodhall prime

    and it's sexy prime (look that one up)

  • Cornersteady
    Cornersteady Club Member Posts: 14,425 ✭✭✭
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    edited September 2017 #13

    well done Wilson, I wonder who'd spot that one first

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #14

    It's a sexy prime twin too! Yes, here is the  sexy prime 'bedfellow' for 383

     389surprised

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #15

    Really wanted it to be a sexy prime triplet but alas notundecided it does have a cousin prime too though! Look that one up!

  • NevChap
    NevChap Forum Participant Posts: 180
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    edited September 2017 #16

    Mickeysf, surely the reason base ten is the norm is because we have ten digits on our hands.

    What do you call a judge without thumbs? Justice fingers of course!

  • KeithandMargaret
    KeithandMargaret Forum Participant Posts: 660
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    edited September 2017 #17

    Which number is the odd one out - and why?

    6, 22, 40, 51, 57, 77, 81


    Many thanks for your attempts at solving the question.

    You'll love this.

    The answer is 40 – all the others come with Rice.

    I'll get my coat.

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #18

    40 is sweet & sour King prawns on the menu I'm reading, it comes with boiled rice but you can pay extra to change that to fried rice. 

    6 is also an odd one out as its a single digit number. It's also prawn toast (without rice) 

    81 is also an odd one out as its Chicken Maryland and as such is the only one which is not a Chinese dish.wink

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #19

    Can any one fill in the spaces and explain this sequence.

    ...._,13,_,34,_....

    The key to the middle number may open the door to the puzzle!

     

  • moulesy
    moulesy Forum Participant Posts: 9,402 ✭✭✭✭✭
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    edited September 2017 #20

    If I said I knew the answer to that would you think I was telling fib(onnaci)s, mickey? wink 

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #21

    Yep, on an upward spiral!wink

  • Navigateur
    Navigateur Forum Participant Posts: 3,880
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    edited September 2017 #22

    63a here is prawn balls.   Never seen them that size before.

     

     

  • cyberyacht
    cyberyacht Forum Participant Posts: 10,218
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    edited September 2017 #23

    Decimal system - why do you think we have ten digits on our mitts? Ain't nature wonderful.

  • Kennine
    Kennine Forum Participant Posts: 3,472
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    edited September 2017 #24

    Is there a Mathematician in the house?   ---------- No wink

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited September 2017 #25

    How about this number missing from the sequence below?

    70, 836, ????, 5830

  • Busyelf
    Busyelf Forum Participant Posts: 76
    edited May 2019 #26

    I'm gonna say 6 because it's the only single digit whole number. KISS (keep it simple, stupid).

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