Classic Logic & Mini Logic
A negative clue eliminates a match and may combine with another clue to reveal the answer.
Interactive lesson
Every Clue Matters
How one small fact can unlock an entire logic problem
A logic problem may give you everything you need before you make your first deduction. The challenge is recognizing the consequences of each fact.
Try it yourself
The Three Mislabeled Boxes
One box holds only apples. One holds only oranges. The third holds both apples and oranges.
Each box has a label, but there is one crucial fact:
Every box is labeled incorrectly.
You may draw one fruit from one box. Which box should you choose?
Choose a box to test your reasoning.
Because its label is wrong, the box marked APPLES & ORANGES cannot be the mixed box. It must contain only apples or only oranges. One fruit will tell us which.
You drew .
Now follow what that single draw forces to be true.
The key takeaway
The draw confirmed the answer. The setup unlocked it.
The most important clue was not the fruit you drew. It was the fact you knew before touching a box: every label was wrong.
When you read a logic puzzle, ask:
- What does each fact eliminate?
- What must now be true?
Read the entire setup before you begin. A sentence that sounds like background information may control the whole solution.
Use the same thinking
Every puzzle turns facts into limits
Binary
Existing numbers restrict what can legally appear beside them.
Futoshiki
An inequality constrains both cells and works together with row and column rules.
Sherlogic
A detail in the story may be evidence, not merely atmosphere.