If you’re like me, you probably haven’t had to solve a tricky math problem or tackle an algebraic equation since high school—and for that, you’re thankful.
I’ve always understood that some people are naturally drawn to math, while others (myself included) find it less than enjoyable. I’ve always considered myself more of a creative thinker than a logical one. But hey, everyone’s different.
That said, even though math wasn’t my favorite subject in those stuffy, crowded classrooms, I’ve surprisingly developed a certain fondness for solving puzzles and riddles I come across online. It’s something I do at my own pace—never in a rush—and I’ve grown to appreciate the satisfaction that comes from working through these challenges.
And I know I’m not alone. There are countless others who take pride in spotting patterns and cracking complex math problems. With that in mind, we decided to put our readers to the test with a brainteaser that has stumped many people across the internet.
Ready to flex your mathematical muscles? Here’s the problem:
If 1 + 4 = 5, 2 + 5 = 12, and 3 + 6 = 21, then what is 5 + 8?
At first glance, this puzzle seems straightforward, but it has left much of the internet scratching their heads. The answer depends on how you approach the problem, as there are multiple methods—and, surprisingly, more than one correct answer!
Multiple Solutions
Here are five different ways to solve the problem:
Solution One
1 + 4 = 5
2 + 5 = 2 + 2(5) = 12
3 + 6 = 3 + 3(6) = 21
5 + 8 = 5 + 5(8) = 45
Algorithm: A+A(B)=CA + A(B) = C
Answer: 45
Solution Two
1 + 4 = 1 + 4 + (0) = 5
2 + 5 = 2 + 5 + (5) = 12
3 + 6 = 3 + 6 + (12) = 21
5 + 8 = 5 + 8 + (21) = 34
Algorithm: A+B+C′=CA + B + C’ = C, where C′C’ is the previous answer
Answer: 34
Solution Three
1 + 4 = 5 = 5
2 + 5 = (5 + 2) + (5) = 12
3 + 6 = (7 + 2) + (12) = 21
5 + 8 = (9 + 2) + (21) = 32
Algorithm: For X=5,C=X+C′,X=X+2X = 5, C = X + C’, X = X + 2; AA and BB are not used in the equation.
Answer: 32
Solution Four
1 + 4 = 5
2 + 5 = 7 (base 5) = 12
3 + 6 = 9 (base 4) = 21
5 + 8 = 13 (base 3) = 111
Algorithm: Convert A+BA + B to decreasing bases starting from base 6.
Answer: 111
Solution Five
1 + 4 = 5
2 + 5 = 7 (base 5) = 12
3 + 6 = 9 (base 4) = 21
4 + 7 = 11 (base 3) = 102
5 + 8 = 13 (base 2, binary) = 1101
Algorithm: Similar to Solution Four but includes “missing” numbers in base conversion.
Answer: 1101
What Did You Get?
Did your answer match any of the above? Let us know in the comments section on Facebook! This problem has been a source of endless debate online, with no single answer being definitively correct. What it truly demonstrates is that the method you choose can completely change the outcome—a reminder of how fascinating and versatile math can be!
