What is Number Theory?
Number Theory is a branch of pure mathematics that focuses on the properties and relationships of integers. Often called the “Queen of Mathematics,” it explores concepts such as divisibility, prime numbers, and the solutions of equations in whole numbers.
Key Concepts:
Prime Numbers: Natural numbers greater than 1 that have no positive divisors other than 1 and themselves.
Divisibility: Rules and properties determining how one number divides another.
Greatest Common Divisor (GCD): The largest number that divides two or more integers without a remainder.
Modular Arithmetic: A system of arithmetic for integers, where numbers “wrap around” after reaching a certain value (modulus).
Diophantine Equations: Equations that seek integer solutions.
Congruences: Relationships that show two numbers have the same remainder when divided by a given modulus.
Euler’s Theorem & Fermat’s Little Theorem: Important results in modular arithmetic and number theory.
Applications:
Cryptography: The backbone of modern encryption methods like RSA.
Computer Science: Algorithms involving hashing, coding, and data encryption.
Digital Security: Secure communication and authentication systems.
Mathematical Research: Provides deep insight into the structure of numbers.
Coding Theory: Error detection and correction in digital communication.
Number Theory combines elegance with powerful applications in technology, making it one of the most fascinating areas of mathematics.

Number Theory
Shivaji University
Number Theory Notes