## 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?

Share:

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

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?

9. #### Sonya:

the actual answer 316. This is because even though it states what Bill and Carl do to each number, Alice is the one saying it, so you only have to divide by 2 to get the answer. Answer – 316 elm street