Question

Guess my number: Your friend chooses an integer between $0$ and $100$. You have to find out that number by asking questions, but your friend can only answer 'yes' or 'no'. What strategy would you use?

Answer 1

Given,

The number chosen is between $0$ and $100$

Let the number be $x$

I would use the strategy of dividing the interval of possibilities in half after every yes or no answer.

First question would be : whether $x$ lies in $[0,50]$?

If yes, then next question would be : whether $x$ lies in $[0,25]$?

If no, then next question would be : whether $x$ lies in $[50,75]$?

Every next question would be based on the previous answer.

In this way, the interval would be smaller and smaller after every answer and eventually lead to the number in minimum number of questions asked.