perplexus.info :: Logic : William's house-number

William's house-number (Posted on 2013-06-04)

William lives in a street with house-numbers 8 up to 100. Lisa wants to know at which number William lives.

She asks him: "Is your number larger than 50?"
William answers, but lies.
Upon this, Lisa asks: "Is your number a multiple of 4?"
William answers, but lies again.
Then Lisa asks: "Is your number a square?"
William answers truthfully.
Upon this, Lisa says: "I know your number if you tell me whether the first digit is a 3."
William answers, but now we don't know whether he lies or speaks the truth.

Thereupon, Lisa says at which number she thinks William lives, but (of course) she is wrong.

What is William's real house-number?

See The Solution Submitted by K Sengupta

Rating: 5.0000 (1 votes)

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
No Subject	K Sengupta	2022-06-09 04:08:57
Maths	Howard Echeverria	2022-06-09 04:06:05
a d1 answer	Ady TZIDON	2013-06-04 13:05:03
computer-assisted solution	Charlie	2013-06-04 11:40:43
Solution	Bryan	2013-06-04 11:07:30

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