

Concept check | P&C | Number of ways in which distinct rings can be put into the given fingers

Concept check | Coin Paradox | Numerical solution to SAT problem | A circle roling on another circle

Concept Check | Linear vs Circular permutation Ways to paint 6 faces of cube with 6 different colors

Combinations: A very common beginner's' doubt in combinations

Concept check | Condition that all the roots of f(x)=f^-1(x), f(f(x))=x are exactly same as f(x)=x
