before d exam day ∆
It was the first day of our second semester and we were looking for our hostel room numbers allotted, we saw that one of our friend was already allotted the room number last night and he challenged us to guess his new room number. We gave following answers
135, 780, 785 and 732.
He said, “That’s amazing”, “You’ve each guessed exactly one digit correctly and in its right place!”
Now can you guess what is his room number ?
The answer is 182.
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1 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, i.e. 2.