Where is the Party?

One day you meet your friend Alice enjoying a nice walk with her husband Bob and their son Carl. They are excited to see you and they invite you to their party.

Alice: Please, come to our party on Sunday at our place at 632 Elm St. in Watertown.
Bob: My wife likes exaggerating and multiplies every number she mentions by 2.
Carl: My dad compensates for my mom’s exaggerations and divides every number he mentions by 4.
Alice: Our son is not like us at all. He doesn’t multiply or divide. He just adds 8 to every number he mentions.

Where is the party?

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8 Comments

  1. Rosario:

    With a as Alice’s multiplicator and n as the house number I get:

    n * 2(4-(8/a)) = 632

    Only a=4 works out (632=2^3*79), so n=158.

  2. Chris Hills:

    A multiplies by a
    B divides by b
    C adds 8

    B says that a = 2
    C says that b = 4
    A says that c = 8

    So a doesn’t equal 2, it equals 2 * b, so that when B divides that by b he says “a = 2”. Similarly b = 4 – c, and c = 8 / a.

    a = 2b = 8 – 2c = 8 – 16 / a

    a2 = 8a – 16

    a2 – 8a + 16 = 0

    (a – 4)2 = 0

    a = 4
    b = 2
    c = 2

    So the address is 632 / 4 = 158 Elm St.

  3. Chris Hills:

    That should have said C adds c

  4. Konstantin Knop:

    I changed last sentences (sorry my English

    Alice: Please, come to our party on Sunday at our place at 632 Elm St. in Watertown.
    Bob: My wife likes exaggerating and multiplies every number she mentions by 2.
    Carl: My dad compensates for my mom’s exaggerations and divides every number he mentions by 4.
    Alice: Our son is not like us at all. He doesn’t multiply or divide. He just adds __ to every number he mentions.

    I: Sorry, Alice, I’m not listen what’s Carl adding number.
    Alice: Not a matter. Information is enough.

  5. tanyakh:

    Konstantin,

    This is great! The exact number that Carl uses is not needed.

    You can say it like this:

    I: Sorry, I didn’t hear Carl’s adding number.
    Alice: It doesn’t matter. You have enough information to find our party.

  6. Albert and Bernard - Helix @ CSIRO:

    […] A different party brainteaser […]

  7. Chris:

    Konstantin and Tanya. Not true. If you don’t hear Alice say 8 then a cannot be calculated eg If Alice says 6 then a =2 and a=6 are both possible.

  8. perlexed:

    Question:
    If they’re such great friends, shouldn’t they know each other’s address?