If 9999 = 4, 8888 = 8, 1816 = 3, and 1212 = 0, then 1919 = 2. This puzzle is a bit tricky yet by understanding and analyzing well the puzzle you will come up with the most appropriate answer. 9999 = 4, 8888 = 8, 1816 = 3, 1212 = 0, and 1919 = 2 because you only count the circles or round shape seen on each number. In 9999, each 9 has 1 circle thus there are 4 circles. In 8888, each 8 has 2 circles resulting to 8 circles. In 1816, 8 has 2 circles and 6 has 1 circle therefore the number has 3 circles. In 1212, you cannot see any circle therefore no or zero circles. And lastly in 1919, there is 1 circle in each 9. Therefore, the answer to this tough puzzle is 2.