Math puzzles always tickle the brain, and this one has tickled quite a few on LinkedIn. Why are these puzzles so popular, and what’s the right answer? I sampled 610 responses to find out.
Of the 610 responses I sampled, the range of answers was surprisingly large, although there were two clear candidates 98 and 99, followed by a less likely third, 101. The full table of counts looks like
x 2 27 40 71 81 82 88 97 98 99 100 101 107 108 113 119 263 1 1 1 1 1 1 1 4 268 293 1 17 1 4 1 10 4
According to the data, 48.1% of respondents said the answer is 99, while 43.9% said it was 98. If we trust the wisdom of the crowds, 99 is the correct answer, yes? Not so fast. This is what makes puzzles like this so popular because multiple plausible answers seem to exist. If there was a clear majority for a particular answer, the puzzle wouldn’t stoke the embers of our emotions. (Other puzzle constructions exist that use different strategies to draw people in.)
Why is 99 incorrect? People used a few different approaches to arrive at this answer. Let’s define a matrix 
Source:: r-bloggers.com