Brain exercise

I have found an amusing riddle, that uses numbers. The text before the riddle stated: “This riddle is solved by 5-year-olds in 5-10 minutes. By computer scientists in about an hour. By people with higher education … well no one waited that long”. So as an IT guy I wanted to take the challenge and get it solved in 5-10 minutes.

Here’s the riddle:

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

2581 = ?

I have tried mathematical approach, but when I have succeeded with one number, my solution didn’t work for one of the others. I am not a good mathematician, so I thought to myself, that maybe this is some kind of a pattern not a numeric expression. And suddenly the answer came to me. I have solved it in about 10 minutes.

My hint for solving it is to switch your thinking and looking at it like a 5-year-old.

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2 thoughts on “Brain exercise

  1. I found I could solve it in under 1 min by quickly abandoning any approach based on numerical patterns. As a translator I have to routinely reject wording that doesn’t work fast in order to clear my mind to find the right words and phrases. Maybe that helped. I studied IT and was a software developer for a time before making a career out of my love of language.

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