Math problem leaves the internet scratching their heads

If you’re like me, math in high school wasn’t fun. I’m more creative than logical, but solving online puzzles has become a guilty pleasure. And I’m not alone—many enjoy spotting patterns and cracking tricky problems.

Here’s a classic brain-teaser:

1 + 4 = 5
2 + 5 = 12
3 + 6 = 21
5 + 8 = ?

It’s left much of the internet stumped, and there’s more than one solution. Here are five ways to solve it:

Solution 1 (A + A×B):
5 + 8 = 5 + 5×8 = 45

Solution 2 (Add previous answer):
5 + 8 = 5 + 8 + 21 = 34

Solution 3 (Sequence formula):
5 + 8 = (9 + 2) + 21 = 32

Solution 4 (Decreasing base system):
5 + 8 = 13 in base 3 = 111

Solution 5 (Decreasing base with missing numbers):
5 + 8 = 13 in base 2 = 1101

Multiple correct answers exist, depending on the method you choose.