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Wolfram Language & System Documentation Center
Mod
  • See Also
    • PowerMod
    • Quotient
    • QuotientRemainder
    • Divisible
    • CoprimeQ
    • ModularInverse
    • FractionalPart
    • PolynomialMod
    • PolynomialRemainder
    • PolynomialQuotientRemainder
    • Xor
    • Modulus
  • Related Guides
    • Integer Functions
    • Mathematical Functions
    • Differential Equations with Events
    • Number Theory
    • Number Theoretic Functions
    • Representation of Numbers
    • Numerical Functions
    • Cryptographic Number Theory
    • Conditionals
    • Additive Number Theory
    • Multiplicative Number Theory
  • Tech Notes
    • Some Mathematical Functions
    • Integer and Number Theoretic Functions
    • See Also
      • PowerMod
      • Quotient
      • QuotientRemainder
      • Divisible
      • CoprimeQ
      • ModularInverse
      • FractionalPart
      • PolynomialMod
      • PolynomialRemainder
      • PolynomialQuotientRemainder
      • Xor
      • Modulus
    • Related Guides
      • Integer Functions
      • Mathematical Functions
      • Differential Equations with Events
      • Number Theory
      • Number Theoretic Functions
      • Representation of Numbers
      • Numerical Functions
      • Cryptographic Number Theory
      • Conditionals
      • Additive Number Theory
      • Multiplicative Number Theory
    • Tech Notes
      • Some Mathematical Functions
      • Integer and Number Theoretic Functions

Mod[m,n]

gives the remainder on division of m by n.

Mod[m,n,d]

uses an offset d.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Numerical Evaluation  
Symbolic Manipulation  
Applications  
Basic Applications  
Numeric Identifiers  
Cryptography  
Show More Show More
Number Theory  
Computer Sciences  
Politics, Economics and Social Sciences  
Other Applications  
Properties & Relations  
Possible Issues  
Neat Examples  
See Also
Tech Notes
Related Guides
Related Links
History
Cite this Page
BUILT-IN SYMBOL
  • See Also
    • PowerMod
    • Quotient
    • QuotientRemainder
    • Divisible
    • CoprimeQ
    • ModularInverse
    • FractionalPart
    • PolynomialMod
    • PolynomialRemainder
    • PolynomialQuotientRemainder
    • Xor
    • Modulus
  • Related Guides
    • Integer Functions
    • Mathematical Functions
    • Differential Equations with Events
    • Number Theory
    • Number Theoretic Functions
    • Representation of Numbers
    • Numerical Functions
    • Cryptographic Number Theory
    • Conditionals
    • Additive Number Theory
    • Multiplicative Number Theory
  • Tech Notes
    • Some Mathematical Functions
    • Integer and Number Theoretic Functions
    • See Also
      • PowerMod
      • Quotient
      • QuotientRemainder
      • Divisible
      • CoprimeQ
      • ModularInverse
      • FractionalPart
      • PolynomialMod
      • PolynomialRemainder
      • PolynomialQuotientRemainder
      • Xor
      • Modulus
    • Related Guides
      • Integer Functions
      • Mathematical Functions
      • Differential Equations with Events
      • Number Theory
      • Number Theoretic Functions
      • Representation of Numbers
      • Numerical Functions
      • Cryptographic Number Theory
      • Conditionals
      • Additive Number Theory
      • Multiplicative Number Theory
    • Tech Notes
      • Some Mathematical Functions
      • Integer and Number Theoretic Functions

Mod

Mod[m,n]

gives the remainder on division of m by n.

Mod[m,n,d]

uses an offset d.

Details

  • Mod is also known as modulo operation.
  • Mathematical function, suitable for both symbolic and numerical manipulation.
  • Typically used in modular arithmetic, cryptography, random number generation and cyclic operations in programs.
  • Mod[m,n] gives the remainder of m divided by n.
  • Mod[m,n] is equivalent to m-n Quotient[m,n].
  • For positive integers m and n, Mod[m,n] is an integer between 0 and n-1.
  • Mod[m,n,d] gives a result such that and .

Examples

open all close all

Basic Examples  (4)

Compute 5 mod 3:

The remainder on division of 5 by 3 offset to start with 1:

Plot the sequence with fixed modulus:

Plot the sequence, varying the modulus:

Scope  (13)

Numerical Evaluation  (6)

Compute using integers:

Compute using an offset:

Mod works on integers:

Rational numbers:

Real numbers:

Complex numbers:

Exact numbers:

Inexact number:

Compute using large integers:

Mod threads over lists:

TraditionalForm formatting:

Symbolic Manipulation  (7)

Solve a modular equation:

Use Mod in a sum:

Product:

Simplify an expression:

Identify Mod sequences:

Recurrence equation:

DirichletTransform:

Generating function:

Applications  (19)

Basic Applications  (3)

The first 20 values of Mod:

Plot the sequence with a fixed modulus:

Plot the sequence, varying the modulus:

Generating function of Mod[n,8]:

Exponential generation function:

Dirichlet series:

Numeric Identifiers  (1)

Given an International Standard Book Number (ISBN), check whether or not it is valid:

An ISBN is valid if , where each is the digit of the ISBN:

Check if each of the ISBNs are valid:

Cryptography  (2)

Build an RSA-like encryption scheme. Start with the modulus:

Find the universal exponent of the multiplication group modulo n:

Private key:

Public key:

Encrypt a message:

Decrypt it:

Use Mod to create a Caesar cipher that shifts letters in the alphabet to encrypt a message:

Encrypt a message with a key:

Decrypt the message:

Number Theory  (6)

Check if numbers of the form are prime or composite:

Select primes below 100 having the form of :

Fermat's little theorem:

Euler's theorem:

Wilson's theorem:

Define a notation for addition modulo 2:

Use Mod to solve systems of linear congruences:

Computer Sciences  (3)

Create a random number generator that uses the current time as a seed:

Choose a modulus and base:

Compute 1000 random numbers between 0 and 1:

Extract parts of a list cyclically:

Modular computation of a matrix inverse:

First compute the matrix adjoint:

Then compute the modular inverse of a matrix:

Check that the inverse gives the correct result:

Politics, Economics and Social Sciences  (2)

Assign memory addresses to social security numbers based on a hashing algorithm:

Assign each social a location, ensuring that there are no collisions:

Compute the result:

Compute the hash of a single social security number:

Other Applications  (2)

Simulate a particle bouncing in a noncommensurate box:

System of 12-tone equal temperament:

Notes that have a difference of 1200 cents are considered to be from the same congruence class:

Properties & Relations  (7)

Mod is a periodic function:

Mod is defined over all complex numbers:

Range:

Mod is transitive. If and , then :

If divides then :

The QuotientRemainder[a,n] is the same as Mod[a,n]:

Use PowerMod to compute the modular inverse:

Check the result:

The results have the same sign as the modulus:

For a positive real number x, Mod[x,1] gives the fractional part of x:

Possible Issues  (1)

Some computations may require higher internal precision than the default:

Reset the value of $MaxExtraPrecision:

Neat Examples  (4)

Binomial coefficients modulo 2:

Additive cellular automaton:

Plot of an Ulam spiral where numbers are colored based on their congruence modulo 49:

Modular addition tables:

See Also

PowerMod  Quotient  QuotientRemainder  Divisible  CoprimeQ  ModularInverse  FractionalPart  PolynomialMod  PolynomialRemainder  PolynomialQuotientRemainder  Xor  Modulus

Tech Notes

    ▪
  • Some Mathematical Functions
  • ▪
  • Integer and Number Theoretic Functions

Related Guides

    ▪
  • Integer Functions
  • ▪
  • Mathematical Functions
  • ▪
  • Differential Equations with Events
  • ▪
  • Number Theory
  • ▪
  • Number Theoretic Functions
  • ▪
  • Representation of Numbers
  • ▪
  • Numerical Functions
  • ▪
  • Cryptographic Number Theory
  • ▪
  • Conditionals
  • ▪
  • Additive Number Theory
  • ▪
  • Multiplicative Number Theory

Related Links

  • MathWorld
  • The Wolfram Functions Site
  • An Elementary Introduction to the Wolfram Language : More about Numbers
  • NKS|Online  (A New Kind of Science)

History

Introduced in 1988 (1.0) | Updated in 1996 (3.0) ▪ 1999 (4.0) ▪ 2000 (4.1) ▪ 2002 (4.2)

Wolfram Research (1988), Mod, Wolfram Language function, https://reference.wolfram.com/language/ref/Mod.html (updated 2002).

Text

Wolfram Research (1988), Mod, Wolfram Language function, https://reference.wolfram.com/language/ref/Mod.html (updated 2002).

CMS

Wolfram Language. 1988. "Mod." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2002. https://reference.wolfram.com/language/ref/Mod.html.

APA

Wolfram Language. (1988). Mod. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Mod.html

BibTeX

@misc{reference.wolfram_2025_mod, author="Wolfram Research", title="{Mod}", year="2002", howpublished="\url{https://reference.wolfram.com/language/ref/Mod.html}", note=[Accessed: 01-December-2025]}

BibLaTeX

@online{reference.wolfram_2025_mod, organization={Wolfram Research}, title={Mod}, year={2002}, url={https://reference.wolfram.com/language/ref/Mod.html}, note=[Accessed: 01-December-2025]}

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