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# KCC's Quizzes: Strange Coding

A special coding is used to compress 4-digits numbers into one. Can you crack it by giving the value for the last number (in red)?

 8809 = 6 5555 = 0 7111 = 0 8193 = 3 2172 = 0 8096 = 5 6666 = 4 1012 = 1 1111 = 0 7777 = 0 3213 = 0 9999 = 4 7662 = 2 7756 = 1 9313 = 1 6855 = 3 0000 = 4 9881 = 5 2222 = 0 5531 = 0 3333 = 0 2581 = ?

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[edited by: emassa at 8:41 PM (GMT -4) on 13 Mar 2023]
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• Each digit in the 4 digit number has a value associated with it, and the result is the sum of those values.

1111, 2222, 3333, 5555, and 7777 all have zero as a result, so 1, 2, 3, 5, and 7 digits are all have a value of zero.

0000, 6666, and 9999 have 4 as a result, so 0, 7 and 9 have a value of 1.

8809 =6, so the digit 8 must have a value of 2 (2+2+1+1)

From the above we now know that 2581=0+0+2+0=2

• Counting the number of loops in each digit as Mark answered with also explains why the digit 4 doesn't show up at all.  I guess it's not clear if 4's have a loop/enclosed space or not!