You need to count the number of round elements in each string. For example, in first line, “8809” contains six round elements (two in each “8”, one in “0”, one in “9”). Next line, “7111” does not contain round elements at all. And so on.
P.S. Sorry, took me a little longer 🙂
The following problem is offered to kids admitted to kindergarten or first-grade in some of the Ukrainian schools. I couldn’t solve this problem immediately, had to look for a solution. For readers of this post I’ll let out a small hint – the problem is much simpler then you first think.
8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9312 = 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 = ?
If you really must know the solution -I’ll post it tomorrow.