Proof of Bertrand's postulate

Bertrand's postulate, also known as Bertrand's theorem, states that for any integer \( n > 1 \), there exists at least one prime number \( p \) such that \( n < p < 2n \). In simple terms, the theorem asserts that there is always at least one prime number between any number \( n \) and its double \( 2n \).