If 8809 equals 6 and 7111 equals 0 and 2172 equals 0 and 6666 equals 4 what is 2581 equal to?

The solution is to count how many circles there are in each number. For instance, since the numeric value eight (8) contains two circles, the numeric value zero (0) is one circle and the numeric value nine (9) contains one circle, 8809 contains a grand total of six circles. The rest of the numbers in the problem are below with the numbers containing circles bolded.

8809=6 circles

7111=0 circles

2171=0 circles

6666=4 circles

so....2581=2 circles