John is tryng to locate Tom's house. All he knows is that Tom lives on a street with houses numbered from 8 to 100.

John asks Tom:

"Is your house number bigger than 50?"

Tom answers him, but he lies. (John doesn't know that he's lying) John continues to ask:

"Is your house number a multiple of 4?"

Tom answers and again, he lies. Then John asks:

"Is your house number the square of an integer?"

Tom answres, but this time he tells the truth. Finally, John asks:

"Is the first digit of your house number 3?"

After Tom answers (we don't know if he lied or not) John declares Tom's house number, but he is wrong! What is Tom's house number?

We make the assumption that John believed Tom to be "Knightly".

John's pattern of questions indicated that Tom answered the first three questions:

• "No, my house number is not bigger than 50."
• "Yes, my house number is a multiple of 4."
• "Yes, my house number is the square of an integer."

John at this point believes the house number to be either 16 or 36. Yet, as Tom lied in his first two answers and told the truth with his third, (the answer to the question - "Is the first digit of your house number 3?" - being irrelevant), only one possible house number remains. Tom's house number is 81.

Posted by Dej Mar on 2008-02-14 03:43:36