Ok, I think I got something. The answer should be :
1960.
The ancient civilization
had a numbering system based on the base 3, as it has been mentioned in the comments and in the hint. Thus, they only had digits 0, 1 and 2.
The operation *|*
is performed :
on each digit of a number like this:
> If the 2 digits are the same, then the result is the same.
That gives us :
0 *|*
0 = 0
1 *|*
1 = 1
2 *|*
2 = 2
> If the digits are different, then the result is the last remaining digit
That gives us :
0 *|*
1 = 2
1 *|*
2 = 0
2 *|*
0 = 1
Now, the real problem. In order to obtain the result for 2 numbers, we have to
convert the numbers to their representation in base-3. Then, we apply the operation digit by digit.
For example, 421 *|*
379 gives 120121 *|*
112001 which gives 101211, and converted back to decimal : 292.
And now, all the values in the question :
21 *|*
7 = 11
0000000210 *|*
0000000021 = 0000000102
10 *|*
23 = 6
0000000101 *|*
0000000212
1 *|*
0 = 2
0000000001 *|*
0000000000 = 0000000002
17924 *|*
10751 = 851
0220120212 *|*
0112202012 = 0001011112
With, of course, the final answer :
1982 *|*
2010 = 1960
0002201102 *|*
0002202110 = 0002200121