Brain teasers are more than just a fun distraction — they’re powerful tools for mental fitness. Engaging with puzzles and riddles activates parts of the brain linked to memory, logic, and concentration. Regular mental challenges can sharpen problem-solving abilities, encourage creative thinking, and even help delay cognitive decline. That’s why brain teasers have become wildly popular on social media, where users love putting their minds to the test — and sharing the challenge with others.
Also read: Maths test: Crack this mind-bending brain teaser to earn the title of puzzle pro
One such puzzle has been making waves on X (formerly Twitter), shared by Brainy Bits Hub. The image presents a sequence of math equations with a twist:
If 2 + 1 = 3 and 4 + 3 = 21 and 6 + 5 = 55 Then 5 + 4 = ?
At first glance, these equations don’t follow traditional math rules, especially the second and third equations. The teaser dares viewers to figure out the logic behind these seemingly incorrect statements — and apply that logic to solve the final equation.
Take a look at the post
Many took to the comments section to react. A user wrote, “?=(5+4)*4= 36”
{{/usCountry}}Many took to the comments section to react. A user wrote, “?=(5+4)*4= 36”
{{/usCountry}}Another added, “[A+B]*B=36”
Here’s the trick: the pattern follows a simple formula — add the two numbers, then multiply the result by the second number. So, for the first equation: (2 + 1) × 1 = 3. For the second: (4 + 3) × 3 = 21. And the third: (6 + 5) × 5 = 55. Once you spot the pattern, the solution becomes clear.
Applying the same logic to 5 + 4:
(5 + 4) × 4 = 9 × 4 = 36
So, the final answer is 36.