Admit it: the mere mention of “math” can conjure up memories of crumpled notebooks and spreadsheets filled with mysterious numbers. Yet, when a little challenge pops up online, it’s impossible to resist. We tell ourselves, “Okay, just to see”… and ten minutes later, we’re frowning, redoing the calculations over and over again. This particular problem has put thousands of internet users in this exact state. And you’ll soon understand why.
The mathematical challenge that is causing debate
It all begins with a series of additions that, at first glance, seem perfectly ordinary:
1 + 4 = 5
2 + 5 = 12
3 + 6 = 21
5 + 8 = ?
Instinctively, our brain seeks a simple logic. A classic addition? Obviously not. Otherwise, the mystery wouldn’t exist. And that’s where things get interesting: depending on the logic you adopt, several answers can be considered correct.
