Modulo Calculator

  • Enter two numbers in the "Enter a number" and "Enter a modulus" fields.
  • Click the "Calculate" button to calculate the modulo.
  • The result and the detailed calculation will be displayed below.
  • Your calculation history will be listed in the "Calculation History" section.
  • Click "Clear" to reset the input fields and result.
  • Click "Copy Result" to copy the result to the clipboard.

Detailed Calculation:

Calculation History:


    Modular arithmetic is a fundamental mathematical concept that deals with the remainder when one integer is divided by another. It finds applications in various fields, including computer science, cryptography, and number theory. The Modulo Calculator is a valuable tool that simplifies modular arithmetic calculations, making them accessible and efficient.

    What is Modular Arithmetic?

    Modular arithmetic, also known as clock arithmetic, operates within a fixed range of integers, called the modulus. It is denoted as “a mod m,” where ‘a’ is the integer being operated upon, and ‘m’ is the modulus. The result of this operation is the remainder when ‘a’ is divided by ‘m.’ In other words, it represents the position of ‘a’ on a hypothetical clock face with ‘m’ divisions.

    Formulae in Modular Arithmetic

    1. Addition in Modular Arithmetic
      • (a + b) mod m = (a mod m + b mod m) mod m
    2. Subtraction in Modular Arithmetic
      • (a – b) mod m = (a mod m – b mod m) mod m
    3. Multiplication in Modular Arithmetic
      • (a * b) mod m = (a mod m * b mod m) mod m
    4. Exponentiation in Modular Arithmetic
      • a^n mod m = (a mod m)^n mod m
    5. Modular Inverse
      • The modular inverse of ‘a’ modulo ‘m’ (a^(-1) mod m) exists if ‘a’ and ‘m’ are coprime, and it satisfies the equation: (a * a^(-1)) mod m = 1

    Example Calculations

    Let’s illustrate these formulae with some example calculations:

    Example 1: Addition in Modular Arithmetic

    Suppose we want to calculate (23 + 17) mod 12:

    (23 + 17) mod 12 = (40) mod 12 = 4

    Example 2: Multiplication in Modular Arithmetic

    Let’s find (8 * 6) mod 5:

    (8 * 6) mod 5 = 48 mod 5 = 3

    Example 3: Modular Exponentiation

    Calculate (2^5) mod 7:

    (2^5) mod 7 = 32 mod 7 = 4

    Example 4: Modular Inverse

    Find the modular inverse of 3 modulo 11:

    3^(-1) mod 11 = 4, as (3 * 4) mod 11 = 1

    Real-World Use Cases

    Modular arithmetic and the Modulo Calculator have a wide range of practical applications:


    In cryptography, modular arithmetic is the basis for many encryption algorithms. Public-key encryption methods like RSA rely on modular arithmetic operations for secure data transmission and encryption key generation.

    Computer Science

    Modular arithmetic is used in computer science to address issues related to cyclic data structures and ensure efficient memory allocation. It is also valuable in hashing algorithms, which play a crucial role in data retrieval and indexing.

    Error Detection and Correction

    In data communication and storage, modular arithmetic helps detect and correct errors. Techniques like checksums and error-correcting codes leverage modular arithmetic to verify data integrity.

    Digital Clocks and Calendars

    Digital clocks and calendars use modular arithmetic to display time and dates. For instance, a clock with a modulus of 12 displays time in a 12-hour format.

    Game Development

    Game developers use modular arithmetic to create looping animations, simulate cyclic behaviors, and manage game events. It ensures seamless transitions and periodic events in video games.


    The Modulo Calculator is a powerful tool that simplifies modular arithmetic calculations, allowing for easy manipulation of integers within a defined range. We have explored the concept of modular arithmetic, discussed essential formulae, provided example calculations, and highlighted real-world use cases across various domains.


    1. Rosen, K. H. (2009). “Elementary Number Theory and Its Applications” (6th ed.). Pearson Education.
    2. Shoup, V. (2006). “A Computational Introduction to Number Theory and Algebra.” Cambridge University Press.

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