1. not quite sure.help!
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    13 Oct '07 19:42
    ok this will be very easy as i got it in just a few seconds myself but its fun to do nonetheless. find a number that is:

    a number between 1 & 36
    two digits
    a multiple of 3
    when the digits are added together the sum is between 4 & 8
    is odd
    when you multiply the digits the product is between 4 & 8

    what is the number?
  2. Standard memberwolfgang59
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    13 Oct '07 19:54
    15 ... perhaps others?
  3. Standard memberDutch Defense
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    13 Oct '07 19:57
    Originally posted by wolfgang59
    15 ... perhaps others?
    looks good
  4. not quite sure.help!
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    13 Oct '07 21:081 edit
    yeah 15 is correct. i wish i was able to put triangles on here then i can do some of my other puzzles but i think i can do it here lets see.

    6 5 3 ?


    1 2 1 3

    2 3 1 2 2 1 2 3


    what is "?"




    shoot it doesnt work. ok from top to bottom.
    6,1,2 3
    5,2,1 2
    3,1,2 1
    ?,3,2 3
  5. Diverse City
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    13 Oct '07 23:56
    Originally posted by tournymangr
    ok this will be very easy as i got it in just a few seconds myself but its fun to do nonetheless. find a number that is:

    a number between 1 & 36
    two digits
    a multiple of 3
    when the digits are added together the sum is between 4 & 8
    is odd
    when you multiply the digits the product is between 4 & 8

    what is the number?
    15 r 17
  6. Joined
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    14 Oct '07 01:16
    Originally posted by Sargent Carpface
    15 r 17
    Just 15

    n x 3 =/= 17
  7. Subscriberjoe shmo
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    14 Oct '07 01:58
    Originally posted by wolfgang59
    15 ... perhaps others?
    wait....the sum of 1 and 5 is 6, which is not an odd number?
  8. Subscriberjoe shmo
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    14 Oct '07 02:051 edit
    I find no numbers that meet all the criteria?
  9. Subscriberjoe shmo
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    14 Oct '07 02:26
    Has anyone noticed the sum of the digits of multiples of 3 repeat 3,6,9 up until 39 which its sum is 12, which has a sum of 3 restarting the sequense replacing a sum of 12 fo three. can anyone explain this?
  10. Subscriberjoe shmo
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    14 Oct '07 02:55
    Originally posted by joe shmo
    wait....the sum of 1 and 5 is 6, which is not an odd number?
    whoops, the odd part does not belong to the sum stipulation...........nevermind 😳
  11. Standard memberTheMaster37
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    14 Oct '07 11:51
    Originally posted by joe shmo
    Has anyone noticed the sum of the digits of multiples of 3 repeat 3,6,9 up until 39 which its sum is 12, which has a sum of 3 restarting the sequense replacing a sum of 12 fo three. can anyone explain this?
    Yup, it's a way to check if a number is a multiple of three;

    Have a number abc (where a, b and c stand for the single digits of a three-digit number).

    You can write it as a * 100 + b * 10 + c * 1

    a * 99 is a multiple of 3, as well as b * 9.

    So abc is a multiple of three

    if and only if

    a * 1 + b * 1 + c * 1 = a + b + c is a multiple of three.

    This works for all numbers.

    So to check if 123456723 is a multiple of three, we calculate 1+2+3+4+5+6+7+2+3 = 33.

    To check if 33 is a multiple of three, we calculate 3+3 = 6

    6 is a multiple of 3, so 123456723 is a multiple of three as well.

    You have a similar trick for multiples of 9 (sum of digits must be 9 then) and multiples of 11 (alternating sum of digits must be 0).

    There is even one for multiples of 7, but that's a bit trickier.
  12. Subscriberjoe shmo
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    14 Oct '07 14:32
    Originally posted by TheMaster37
    Yup, it's a way to check if a number is a multiple of three;

    Have a number abc (where a, b and c stand for the single digits of a three-digit number).

    You can write it as a * 100 + b * 10 + c * 1

    a * 99 is a multiple of 3, as well as b * 9.

    So abc is a multiple of three

    if and only if

    a * 1 + b * 1 + c * 1 = a + b + c is a multiple of ...[text shortened]... sum of digits must be 0).

    There is even one for multiples of 7, but that's a bit trickier.
    Thanks, I find that interesting.
  13. Standard memberTheMaster37
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    14 Oct '07 14:45
    Same here! It's funny how numbers can behave so nicely 🙂
  14. Account suspended
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    17 Oct '07 20:59
    Originally posted by TheMaster37
    Yup, it's a way to check if a number is a multiple of three;

    Have a number abc (where a, b and c stand for the single digits of a three-digit number).

    You can write it as a * 100 + b * 10 + c * 1

    a * 99 is a multiple of 3, as well as b * 9.

    So abc is a multiple of three

    if and only if

    a * 1 + b * 1 + c * 1 = a + b + c is a multiple of ...[text shortened]... sum of digits must be 0).

    There is even one for multiples of 7, but that's a bit trickier.
    or, you can just say that if the sum of digits is divisible by three, then the number is divisible by three...
    you can do this multiple times if necessary...
    for example:
    111111111111111111111111111111111111111111111111111111111

    sum of digits is 57 you can say that 57 is divisible by 3 since 5+7 = 12 and 1+2 = 3...
    meanin that the entire number is divisible by three.
  15. not quite sure.help!
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    23 Oct '07 15:37
    wow...i didnt see all this coming on this thread
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