Trying to discover a hidden 4-digit number I got the following hints:

GUESS RESULT
+---------+-------+
| 1 2 3 4  | B B   |
+---------+-------+
| 5 6 7 8  | B B   |
+---------+-------+
| 8 6 9 0  | B R   |
+---------+-------+

B- One of the digits of this guess exists in the hidden number in THE SAME position.
R- One of the digits of this guess exists in the hidden number in ANOTHER position.

What is the number?

The first two rows must account for all the digits, as 2+2=4 hits arrived with no overlapping digits betweenthe two lines.

The only repeat in the same position in line 3 is the 6, so a 6 is in the second position.  The only other repeat, but not in the same position is the 8, so the 8 is really in the fourth position as it was on line 2.

That leaves the only way that the first row could have two digits in the correct position is for them to be the 1 and the 3 in the first and third positions respectively.

The number is 1638.

Posted by Charlie on 2013-11-11 14:03:17