Braingle: 'Guess My House' Brain Teaser

Guess My House

Logic puzzles require you to think. You will have to be logical in your reasoning.

Puzzle ID:	#49582
Fun:	(2.91)
Difficulty:	(1.32)
Category:	Logic
Submitted By:	dalfamnest

Mac's new house number has three digits. When she challenged her friends to guess it, they tried: 135, 780, 785, and 732.

"That's amazing," Mac said. "You've each guessed exactly one digit correctly and in its right place!"

What is Mac's house number?

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Answer

182

Solution:
The first digit must be 1 or 7. It can't be 7 as only one digit is correct in each guess. So it's 1.

The other digits in guess #1 (i.e. 3 and 5) must be incorrect. Therefore, from guess #3, the second digit is 8.

Guess #4 has a correct digit which must be its third - 2.
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Comments

Marple Sep 03, 2012	Excellent! It made me think very hard!
kidkilowatt Sep 05, 2012	Not extraordinarily difficult, but very engaging due to the casual, fun narrative!
BeanSC Sep 07, 2012	Very well done, creative!
dalfamnest Sep 07, 2012	Thanks. It's based on the old "Mastermind" logic game - which I stopped playing in early married life when my wife always beat me! It's fun to write a little storyline to go with the logic.
ImConfused Sep 14, 2012	As my name goes, I'm quite confused. Do the second and third guess share the second digit? or else, what prevents the last digit from being from the 2nd guess instead of the last?
dalfamnest Sep 15, 2012	Hi ImConfused! Yes, the second and third guesses both had the same digit correct. That would have to be the case, as there are only three digits and four people guessing! Hope you enjoyed it, though!
PYTHON Oct 03, 2012	Cool, I liked it!
Jeppydog Nov 03, 2012	GREAT PUZZLE! Elegant! And a lot of fun. Thanks!
HABS2933 Nov 03, 2012	Though easy, very enjoyable.
Jekyll Nov 03, 2012	How can four people each get only one digit right of a three-digit number?
cutebug Nov 03, 2012	I thought it was enjoyable, although very easy.
dalfamnest Nov 03, 2012	At least two of them must have guessed the same digit correctly ... which is part of the logic required to solve it!
corcon Nov 03, 2012	Mind...exploding...
FatHead Nov 03, 2012	Not bad, but a little too easy. I just took a random guess based on the clues, with the first possibility for the hundreds, the next possibility for the tens, and the only remaining possibility for the ones. And it checked!
thecatladycac Nov 03, 2012	Fairly easy - but it is nice having a little brain stimulation, but also having the satisfaction of solving fairly quickly! I enjoyed your teaser!
iggy39 Nov 03, 2012	never was any good at this kind of teaser.
auntiesis Nov 04, 2012	Great teaser even though it was a little on the easy side. The 3 sevens made it easy to get the first number. After that it was a piece of cake.
trewq Feb 21, 2013	great job! at first, it seemed impossible, but after reading it a couple times I got it! (I did write it down though )
DarthXenon Feb 26, 2013	Here's how I found out (and it probably should be the explanation in the answer, as it may be unclear): There are four guesses, which means that one of the digits was repeated twice. The first digit is 1 since 7 was repeated three times, eliminating the first guess. The second digit is 8 since it was repeated twice in the second and third guesses. By process of elimination, 2 is the third digit, which is in the fourth guess.