Missing corner puzzle
Find the missing corner
A compact arithmetic logic puzzle where the operation sits behind the layout.
Quick answer
Answer: 20
The hidden rule doubles the sum. Three plus 5 equals 8, and 8 doubled is 16. Four plus 6 equals 10, and 10 doubled is 20.
How to use it
1
Notice that normal addition does not explain 16.
2
Test a simple transformation after adding.
3
Use the same rule on the second line.
4
Check whether the result stays consistent.
What this trains
Arithmetic reasoning
Hidden-rule detection
Consistency checking
Mental flexibility
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