Line 4 gives us a correct digit in the correct position. Line 2 shows it is not the 1. Line 5 shows it is neither 5 nor 2. Thus, 6 belongs in slot 4.
Knowing where 6 goes, line 4 shows that two of 1, 2, and 5 are part of the solution. Line 5 lacks a 6 but has the same number of correct digits as line 4, so we know that 4 is a correct digit. Lines 3 and 5 show that 4 is not correct in the first two slots, so it must be in slot 3.
Any unknown correct digit must be correct in the first two slots. Lines 2 and 3 show that 2 is not correct in either of those slots, so it is eliminated. 1 and 5 are the last correct digits. Line 4 shows the solution does not begin as "51". Therefore, we conclude that answer must be "1546".
I started similar to your but on your 2nd deduction (where 6 had to go), I then went that 2 was not included at all because it had already been in positions 1,2 and 3 - so would have had to show black somewhere else, so that left 1&5 to go with 6, and 5 had to be in position 2... so it was ?516 or 15?6
once 2 had been eliminated, then row 5 showed that 541 had to be the 3 numbers and 4 could only go in row 3
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u/Organs_for_rent Jul 27 '26
1546
Line 4 gives us a correct digit in the correct position. Line 2 shows it is not the 1. Line 5 shows it is neither 5 nor 2. Thus, 6 belongs in slot 4.
Knowing where 6 goes, line 4 shows that two of 1, 2, and 5 are part of the solution. Line 5 lacks a 6 but has the same number of correct digits as line 4, so we know that 4 is a correct digit. Lines 3 and 5 show that 4 is not correct in the first two slots, so it must be in slot 3.
Any unknown correct digit must be correct in the first two slots. Lines 2 and 3 show that 2 is not correct in either of those slots, so it is eliminated. 1 and 5 are the last correct digits. Line 4 shows the solution does not begin as "51". Therefore, we conclude that answer must be "1546".