Congruence modulo m Sep 14, 2021 · The foundation for our exploration of abstract algebra is nearly complete. How can we find out that $9$? What are the steps that I need to do? Update If I have a Aritmética dos restos, teoria dos números, congruência modular, congruência módulo m, ma14, profmat, matemática superior, álgebra, mesmo resto na divisão, in Se você está vendo esta mensagem, significa que estamos tendo problemas para carregar recursos externos em nosso website. 6. Jul 14, 2022 · Discrete Mathematics: Congruence Modulo mTopics discussed:1) The definition of Congruence Modulo m. gl/JQ8NysCongruence Modulo n Symmetry Proof Dec 11, 2022 · Congruence Modulo m Relation | Sandeep Sir What is the modulus of congruence?What is meaning a ≡ b mod n?How do you solve modulo congruence?What is the formu Congruence Classes Definition We refer to the equivalence classes of (mod n) as residue classes or congruence classes. Suppose \(a, b_{1}, b_{2} \in \mathbb{Z}\). The congruence relation ax ≡ b (mod m) has a solution if the (“unknown”) 数学上,同余(英语:congruence modulo,符号:≡)是数论中的一种等价关系。当两个整数除以同一个正整数,若得相同余数,则二整数同余。同余是抽象代数中的同余关系的原型。最先引用同余的概念与“≡”符号者为德国数学家高斯。由对于模n同余的所有整数组成的这个集合称为同余类(congruence Sep 3, 2022 · This notation for divisibility will be important in the next section on congruence modulo. Hence, every ais congruent modulo m ∴ a − b = λ 1 m for some λ 1 , ∈ Z Similarly b − c = λ 2 m for some λ 2 ∈ Z By (i) and (ii), we have a − c = (λ 1 + λ 2 ) m = km for some k ∈ Z ∴ a − c is divisible by m ∴ a ≡ c (mod m) ∴ Congruence modulo m is transitive on Z. Strictly speaking, congruence modulo m is an “equivalence relation” on the integers Z. Nov 25, 2016 · Below is a more conceptual viewpoint which explains how the congruence equivalence relation is connected with the innate arithmetical structure (we show it is equivalent to a subgroup test). The modular inverse of 7 modulo 48 is 7. Example 3. But when I first learned about the modulo operation my junior year, I would have told you that $13 \equiv 1 \pmod 4$, and that $9 \equiv 4 \pmod 5$. a and b are said to be congruent modulo m, written a ≡ b (mod m), if and only if a – b is divisible by m – … i. 정수환 의 몫환 Z / ( n ) {\displaystyle \mathbb {Z} /(n)} 의 환 구조로 생각할 수 있다. Aug 23, 2022 · In this class, the definition of Congruence is given with examples. If a b (mod m) and c d (mod m), then a+ c b+ d (mod m) and We say that \(a\) is congruent to \(b\) modulo \(m\) if \(m \mid (a-b)\) where \(a\) and \(b\) are integers, i. the definition of congruence modulo $n$: for any two integers $a, b$, $a \equiv b \pmod m \iff a - b = km,$ for some $k \in \mathbb{Z}$. In congruence modulo 5, {x Nov 25, 2024 · Definition: modulo. A solution is an integer x which makes the congruence relation true AND x is a least residue (mod m) (that is, 0 ≤ x ≤ m−1). For any positive integer m, by the division algorithm, we have a= mq+rwhere 0 ≤r≤m−1, and clearly a≡r(mod m). " The number m is called the modulus, and the statement "b is congruent to c (modulo m)" is written mathematically as b=c (mod m). Note. Reflexive only B. 1 Theorem; 2 Proof. It does not produce numbers as output. Thus each integer is in one of the congruence classes: [0];[1 I'm currently stumped on this question: Let $a$ and $m$ be integers such that $m\ge1$. Note that the following conditions are equivalent 1. Definition: given an integer m, two integers a and b are congruent modulo m if m|(a − b). If R is the congruence modulo m relation on the set Z of integers, the set of equivalence Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Apr 17, 2022 · The Division Algorithm. Feb 18, 2019 · Theorem. \(a\) is congruent to \(b\) modulo \(m\) denoted as \( a \equiv b (mod \, n) \), if \(a\) and \(b\) have the Theorem Let m ≥ 2 be an integer and a a number in the range 1 ≤ a ≤ m − 1 (i. Let $z \in \R$. (Re exive Property): a a (mod m) 2. From ProofWiki. ’ For example, 17 and 32 are congruent to modulo 3, which implies 17 ≡ 32 (mod 3). /m71. Thus. Discrete Mathematics: Congruence Modulo mTopics discussed:1) The definition of Congruence Modulo m. Fact There are n distinct congruence classes modulo n. Scratchwork 26 June 25, 2007 21:53 Chapter 3 Congruence Theorem 3. Why is there extra space prefixing the first case. Jump to navigation Jump to search. \(a\) is congruent to \(b\) modulo \(n\) denoted as \( a \equiv b \pmod n \), if \(a\) and \(b\) have the a by the integer m, we get a quotient q and remainder r, 0 ≤ r < m, satisfying the equation a = mq + r. Then $\forall n \in \Z, n \ne 0$: $a \equiv b \pmod m \iff a History: The above theorem is often known as the Chinese Remainder Theorem. If \(a\) is congruent to \(b\) modulo \(m\), we write \(a\equiv b(mod\ m)\). And now xRx because x – x is also divisible by m. cancel cfrom the congruence ac≡bc(mod m) provided (c,m) = 1. See full list on ramanujan. [a]m is called the congruence class of a modulo m. Let $a, b \in \R$ and $m \in \Z$. We will go over 3 ways to interpret a ≡ b (mod n), and you will see this in a number theory or a discret Apr 17, 2022 · Congruence Modulo \(n\) One of the important equivalence relations we will study in detail is that of congruence modulo \(n\). We simply use . , b a = km for some k 2 Z. We write [x] for the congruence class containing x, that is, the set of integers congruent to x modulo m. We write a ≡ b (mod m). We will now look at some simple results regarding congruences. their exists an integer x satisfying the congruence) if and only if b is a multiple of GCD(a,m). 3) Finding the equivalence cla Congruence classes We say two integers are in the same congruence class if they are congruent modulo m. Let $a, b, m \in \Z$. The number ris called the least positive residue modulo m. In congruence modulo 5 we have [3] = f3;3 5;3 10;3 15;g 1. We define a relation $\RR_z$ on the set of all $x, y \in \R$: $\RR_z := \set {\tuple {x, y} \in \R Therefore congruence modulo m is an equivalence relation, and this relation partitions the integers into m equivalence classes: mn + 0, mn + 1, Congruence of Integers Definition 1 When an integer is divided by a non-zero integer , there must be an integral quotient and a remainder , where . For ,, with 0 ≡ (mod )↔ | ( −) Definition: “a is congruent to b modulo m” Integers Domain of Discourse This is a predicate (T/F values) on integers ,, . Question: Congruence Modulo m Example: Let m be an integer with m > 1. If you're seeing this message, it means we're having trouble loading external resources on our website. , [a] = fz 2Z ja z = kn for some k 2Zg : Example: In congruence modulo 2 we have [0] 2 = f0; 2; 4; 6;g [1] 1 = f 1; 3; 5; 7;g : Thus, the congruence classes of 0 and 1 are, respectively, the sets of even and odd integers. Notation: a|b is read "a divides b". The notation is:a ≡ b (mod m) Section 5. The number m is the modulus of the congruence relation. by looking at congruence classes of integers modulo m. . View Solution. So, from the above we can say that the relation R is a reflexive relation. 1. This means the remainder of dividing ‘17 by 3’ and ‘32 by 3’ are 2. 3. In that case we are interested in divisibility by 3 and so we use Euclidean division to separate the integers into 3 cases depending on their remainder. Let a,b be two integers. We have the congruences 3 ≡ −5 (mod 4), 0 ≡ 15 (mod 5), −7 ≡ 5 (mod 6), and 5743 ≡ 43 (mod 100). Because multiples of mare That ring axioms are preserved in congruence rings is simply a derived consequence of the fact that the map to the congruence class $\rm\ n\to [n]\ $ is a homomorphism, i. This will give the smallest positive integer solution. org e *. Solving Linear Congruences Using The Euclidean Algorithm Method. 3) Finding the equivalence cla A special thing about congruence relations is that they divide up the entire set of integers into equivalence classes, called congruence classes modulo \(m\). kasandbox. it preserves all the fundamental operations of the structure. (Transitive Property): If a b (mod m) and b c (mod m), then a c (mod m). Jul 24, 2011 · The smallest integer value in congruence modulo m can be found by dividing the modulus by the remainder of the congruence. Then a is said to be Congruent to b modulo m written a ≡ b (mod m) if m ∣ (a − b). Because of these three properties, we know the set of integers is divided into m different congruence classes modulo m. org are unblocked. For example, Congruence Definitions Let m ∈ N. In fact, a 0 mod m()mja; so the congruence relation includes the divisibility relation as a special case: multiples of m are exactly the numbers that \look like 0" modulo m. a ≡ b (mod m). a = b+km for some integer k. if there is some integer k such that a – b = km Note: this does not directly say a and b have the same remainder upon division by m – That is a consequence of the Basic congruence introduction in modular arithmetic. Congruence Modulo. 同余(英語: Congruence modulo [1] ,符號:≡)在数学中是指數論中的一種等價關係 [2] 。當两个整数 除以同一个正整数,若得相同余数,则二整数同余。同餘是抽象代數中的同餘關係的原型 [3] 。最先引用同余的概念与「≡」符号者为德國 数学家 高斯。 Oct 23, 2021 · Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have In an Introduction to Abstract Algebra by Thomas Whitelaw, he gives examples of the congruence mod operation, such as $13 \equiv5 \pmod4$, and $9 \equiv -1 \pmod 5$. (Symmetric Property): If a b (mod m), then b a (mod m). a and b have the same remainder when divided by m. Please Subscribe here, thank you!!! https://goo. n - r ≡ 0 (mod m) n ≡ r (mod m) Thus the equation n = mq + r through Euclid’s Division lemma can also be written as n ≡ r (mod m). May 24, 2024 · Congruence Modulo. Q3. If \(a \mid b_{1}\) and \(a \mid b_{2}\), then \(a \mid\left(b_{1}+b_{2}\right)\). The relation "congruence modulo m" is: View Solution. Congruences Modulo m. If γ = p n — ε, where ε is a unit, then any congruence modulo γ is equivalent to a congruence modulo p n. Note : Two integers a and b are congruent modulo m, written as . As the congruence modulo is reflexive, symmetric and transitive so it is an equivalence Oct 5, 2022 · In this lecture we are going to learn about congruence modulo m relation. 5 is a good example of this. • We can use congruence to define a system Z m called “the integers modulo m. Hence, for congruence classes modulo 3, if n is a nonnegative integer, then \([10^n] = [1]\). 3 Congruence modulo \(n\) Many results about divisibility of integers involve a fair bit of tedious work involving proof by cases; Result 5. By trying all the residue classes, we see that x3 + 4x 4 (mod 7) has the single solution x 3 (mod 7). We need the basics of one more "number system" in order to appreciate the abstract approach developed in … [a], is the set of all integers that are congruent to a modulo n; i. Notation note: we are using that "mod" symbol in two different ways. 4. 6 (Wilson’s Theorem). 30 tells us that congruence modulo n is an equivalence relation on \(\mathbb{Z}\). Equivalence Classes & Partitions Theorem. The central definition in studying modular arithmetic systems establishes a relationship between pairs of numbers with respect to a special number m called the modulus: Definition 25. Solution of congruence stands for all the values of integer x which are satisfied. In Introduction to Modern Algebra (MATH 4127/5127) and Mod-ern Algebra 1 (MATH 5410) we introduce congruence modulo m as an equiva- Jan 22, 2022 · Example \(\PageIndex{1}\) If \(m=3\) and \(a=7\), we see \[\begin{aligned} \left[7\right] &= \{x:x \equiv 7 \pmod 3\}\\ &= \{\dots, -5, -2, 1, 4, 7, 10, 13, 16, 19 Feb 1, 2021 · 00:39:10 Prove modular congruence theorem (Example #5) 00:47:09 Verify the addition and multiplication congruence identities (Examples #6-7) 00:56:49 Evaluate using modular congruence properties (Examples #8-11) 01:06:42 Arithmetic Modulo m notation (Examples #12-13) 01:10:51 Evaluate using modular arithmetic (Examples #14-17) Apr 17, 2022 · If \(n\) is a nonnegative integer, then \(10^n \equiv 1\) (mod 9), and hence for the equivalence relation of congruence modulo 9, \([10^n] = [1]\). Preview Activity \(\PageIndex{1}\) was an introduction to a mathematical result known as the Division Algorithm. Let $a \equiv b \pmod m$ denote that $a$ is congruent to $b$ modulo $m$. Z m consists of m distinct classes: [0], [1], [2], … , [m – 1]. Two integers, ‘A’ and ‘B,’ are considered congruent under modulo ‘n’ if they yield the same remainder when divided by the positive integer ‘n. 41) that congruence modulo m really is an equivalence relation on Z. If k and m are both odd, then k!m! ≡ 1 (mod p) . 3. Consider the congruence ax ≡ b (mod m) This congruence is solvable (i. In fact, a 0 mod m()mja; so the congruence relation includes the divisibility relation as a special case: the multi-ples of mare exactly the numbers that \look like 0" modulo m. For m a prime, 7l. a − b = k m. Hard space in equation does not work. Show that the relation R = {(a,b) a = b (mod m)} is an equivalence relation on the set of integers. Definition: Modulo. 38. Ex 4 Continuing with example 3 we can write 10 = 5·2. ∗ Let k and m be positive integers and suppose that p = k + m + 1 is a prime. Now we examine the set of equivalence classes with respect to congruence modulo m. Use the division algorithm to write x = nq + r with 0 r < n. ) We have m 0 mod m, and more generally mk 0 mod mfor any k2Z. The relation “congruence modulo $m$” is A. Let R be This is an introduction to congruence in Number Theory. 1 Reflexive; 2. Thus, 3 is relatively prime to 10 and has an inverse The congruence relation, modulo m, partitions the set of integers into m congruence classes. The following relation is defined on the set of Now first of all let us assume the relation of congruence modulo as R. if m | a – b – … i. Since, x r = nq, x r (mod n). Theorem 2: Let . Let x 2Z. 8. Q2. Thus [a] = [r], and so there are exactly m equivalence classes [0],[1],[m−1]. edu modulo m. Proposition 2. In symbols, we write this as a ≡ b mod m. Here, m is a positive integer. CHAPTER 28 Congruence Classes Modulo a Polynomial In Chapter 6 we constructed the rings 7l. Mar 1, 2012 · Carl Friedrich Gauss. This relation is denoted by $$\small{n=m q+r}$$ and the process for getting this relation is called division with remainder. 3 Jun 27, 2019 · En este video explico, de manera sencilla, la definición de congruencia módulo m, dando varios ejemplos de números que son congruentes y números que no lo so A solution for the congruence \(ax\equiv 1 (mod\ m)\) for \((a,m)=1\) is called the modular inverse of \(a\) modulo m. Example 6. Now that we have a better understanding of the modulo operator and some of its related notations, let’s understand one of the most important concepts underlying the Diffie-Hellman key exchange: congruence modulo. (The LaTeX command ncong is for the congruence symbol ˘=in elementary geometry. For finite multisets A,B,C ⊂ Zand any m ∈ N, • A ≡ A(mod m); • if A ≡ B (mod m), then B ≡ A(mod m); and • if A ≡ B (mod m) and B ≡ C (mod m), then A The other equivalence classes are identical to one of the above. a standard rep. The relation of congruence modulo m is an equivalence This is the Solution of Question From RD SHARMA book of CLASS 12 CHAPTER RELATIONS This Question is also available in R S AGGARWAL book of CLASS 12 You can F Oct 1, 2022 · For a positive integer m, a finite set of integers is said to be equidistributed modulo m if the set contains an equal number of elements in each congruence class modulo m. We show below (in Theorem 6. Because multiples of m are congruent to 0 modulo m, we will see that working with integers modulo Sep 14, 2023 · Similar to previous cases of congruence, a and b are integers and m is modulo. What is the purpose of finding the smallest integer value in congruence modulo m? The purpose of finding the smallest integer value in congruence modulo m is to Modular Arithmetic New notion of “sameness” or “equivalence” that will help us understand modular arithmetic. a ≡ b (mod m), if they leave the same remainder when divided by m. Remainder of an integer). Modulo an odd prime number p there are (p + 1)/2 residues (including 0) and (p − 1)/2 nonresidues, by Euler's criterion. So there exists a. This establishes the last part of the theorem. Oct 22, 2023 · Theorem. Definition: Let a, b, m ∈Z. Se você está atrás de um filtro da Web, certifique-se que os domínios *. • For any a,b ∈ Z, we say “a is congruent to b modulo m” if m | (b − a). Because multiples of mare Just as with the usual (integer) congruence modulo m, multiset congruence modulo m is an equivalence relation. Any p-adic integer is congruent to a rational integer modulo p n. First we will see the definition of congruence modulo m relation and then we will The transitive property: If a ≡ b (mod m) and b ≡ c (mod m), then a ≡ c (mod m). Contents. And we know that for a congruence modulo the difference must be divisible by the number. Let abe an integer. if \(a=b+km\) where \(k\in \mathbb{Z}\). Then if and only if there exists a such that . Theorem 1: Let . You now have a set of incongruent solutions given by X = X0 + (M/C)T, where T is given as modulo C. Jan 10, 2025 · If two numbers b and c have the property that their difference b-c is integrally divisible by a number m (i. If a, b, c and d are any integers with a ≡ b (mod m) and c ≡ d (mod m), then a + c ≡ b + d (mod m) a - c ≡ b - d (mod m) This page was last modified on 17 September 2022, at 12:35 and is 1,067 bytes; Content is available under Creative Commons Attribution-ShareAlike License unless Welcome to our Congruence Modulo Calculator! This powerful tool helps you perform modulo operations and check for congruence between numbers. Definition. By definition, a|b if there is some c such that ca = b. An example of this theorem was first discussed by Sun Zi (Chinese mathematician, around 400-460) in his text Sunzi suanjing (Sun Zi’s Mathematical Manual). Given an integer m ≥ 2, we say that a is congruent to b modulo m, written a ≡ b (mod m), if m|(a−b). We thus confine our attention to congruences modulo p n. For example, is congruent to modulo because . Modular arithmetic and integer representations Unsigned, sign-magnitude, and two’s What are some congruence relations apart from congruence modulo $m$? Also, is the congruence modulo $m$ called that way because the sets of all the integers $0,1 Congruence Classes Definition We refer to the equivalence classes of (mod n) as residue classes or congruence classes. trinity. Let \(m\) \(\in\) \(\mathbb{Z_+}\). (i) If x y(mod m), then yis called a residue of xmodulo m; (ii) We say that fx 1;:::;x mgis a complete residue system modulo mif for Let a, b ∈ ℤ, m ∈ ℕ. Gauss (1777–1855) was an infant prodigy and arguably the greatest mathematician of all time (if such rankings mean anything; certainly he would be in almost everyone's list of the top five mathematicians, as measured by talent, accomplishment and influence). This equivalence is written a ⌘ b (mod m). We reviewed this relation in Preview Activity \(\PageIndex{2}\). Theorem 18. Then a has a multiplicative inverse modulo m if a and m are relatively prime. Operations of addition and multiplication can be defined on these m objects in the following way: To either add or multiply two congruence classes, first pick a representative (in any way) from each class, then perform the usual operation for integers on the two representatives and finally take the Congruence mod m. Modulo 2, every integer is a quadratic residue. Jan 28, 2024 · Congruence Modulo Integer is Equivalence Relation. Integers a,b are said to be congruent modulo n if they have the same residue: we write a ≡b (mod n). The proof of the following is straightforward. Proposition 3. Theorem 3. Remark: The above three properties imply that \ (mod m)" is an equivalence relation on the set Z. Let \(n\) \(\in\) \(\mathbb{Z_+}\). Symmetric only D. If you're behind a web filter, please make sure that the domains *. For example: $$7x \\equiv 1 \\pmod{31} $$ In this example, the modular inverse of $7$ with respect to $31$ is $9$. This number is called the least residue of the integer modulo m. e. We denote such a solution by \(\bar{a}\). One of the purposes of this preview activity was to illustrate that we have already worked with this result, perhaps without knowing its name. Proof. A linear congruence is a congruence relation of the form ax ≡ b (mod m) where a,b,m ∈ Z and m > 0. , (b-c)/m is an integer), then b and c are said to be "congruent modulo m. 1. Consider the congruence class of $a$, i. , $[a]$ modulo $m$. ” Z m is defined to be a set with m elements: {[0],[1],[2],,[m − 1]}. So, xRy = x – y is divisible by m. math. I will also sometimes say equivalent modulo m. Next we lift to nd the solutions modulo 72: any solution must be of the form x = 3 + 7a for some a. Congruence modulo a fixed $ m $ is an equivalence relation: it is reflexive, since $ a \equiv a $( $ \mathop{\rm mod}\nolimits \ m $); symmetric, since it follows from $ a \equiv b $( $ \mathop{\rm mod Jan 28, 2024 · Definition. Modular Arithmetic New notion of “sameness” or “equivalence” that will help us understand modular arithmetic. of a number modulo m). Congruence modulo m is a central idea in number theory. The relation "congruence modulo m" is. Transitive only C. If p is a prime, then (p− 1)! ≡ −1 (mod p). Then. 7. Modular arithmetic properties Congruence, addition, multiplication, proofs. Use mathematical induction to prove that if \(n\) is a nonnegative integer, then \(10^n \equiv 1\) (mod 3). In this paper, we consider the problem of determining when the set of gaps of a numerical semigroup S is equidistributed modulo m. 4. 2) Equivalence Classes of R. Example: Solve the congruence x3 + 4x 4 (mod 343). The division algorithm says that every integer a ∈ Z has a unique residue r ∈ Z n . 2. We always have m 0 mod m, and more generally mk 0 mod mfor any k2Z. This is written as \(\mathbb{Z}_m\). Given an integer m ≥ 1, called a modulus, two integers a and b are said to be congruent modulo m, if m is a divisor of their difference; that is, if there is an integer k such that. A linear congruence is similar to a linear equation, solving linear congruence means finding all integer \(x\) that makes, \(ax \equiv b (mod \,m)\) true. Let $a$ be congruent to $b$ modulo $m$, that is: $a \equiv b \pmod m$ Then: $\forall n \in \Z_{\ge 0}: a^n \equiv b^n \pmod . 2 Symmetric; 2. Since 343 = 73, we rst solve the congruence modulo 7, then modulo 72, and then nally modulo 73. kastatic. For any congruence relation on \(\mathbb{Z}\), there are \(m\) congruence classes modulo \(m\), each lining up with all of the possible values of \(b Oct 18, 2021 · Proposition \(5. Two integers a and b are congruent modulo m if they di↵er by an integer multiple of m, i. org and *. May 26, 2024 · The congruence $ a \equiv b \ ( \mathop{\rm mod}\nolimits \ m) $ expresses that $ a $ and $ b $ have identical remainders when divided by $ m $. De nition 1. 7\). Modular arithmetic is a fundamental concept in mathematics with wide-ranging applications in computer science, cryptography, and everyday problem-solving. An equivalence relation The relation "congruence modulo m" is: View Solution. Exercise 3. Also the proof that the congruence relation is an equivalence relation, is explained. Thus each integer is in one of the congruence classes: [0];[1 How to write the congruence modulo n symbol? 3. Mathematically, if C = (A, M) = 1, there is always a definite unique solution for modulo M in the linear congruence AX = B(mod M). The Euclidean Algorithm Method is one of the 수론에서 모듈러 산술(영어: modular arithmetic) 또는 합동 산술(合同算術)은 정수의 합과 곱을 어떤 주어진 수의 나머지에 대하여 정의하는 방법이다. org estão desbloqueados. Find step-by-step Discrete math solutions and your answer to the following textbook question: Show that congruence modulo m is an equivalence relation whenever m is a positive integer. Recall that r = amodm and that a ≡ r(mod m). We also define the ax 1 (mod m), then (ax;m) = (1;m) = 1, which yields a contradiction. 2. Definition by Remainder after Division. The set of congruence classes mod m are denoted by Z m. turned out to be a field. If k and m are both even, then k!m! ≡ −1 (mod p) . In this case, it is customary to consider 0 as a special case and work within the multiplicative group of nonzero elements of the field (/). 30 May 26, 2024 · 2020 Mathematics Subject Classification: Primary: 11A07 [][] A relation between two integers $ a $ and $ b $ of the form $ a = b + mk $, signifying that the difference $ a-b $ between them is divisible by a given positive integer $ m $, which is called the modulus (or module) of the congruence; $ a $ is then called a remainder of $ b $ modulo $ m $( cf. ionknmv eagzeub ngjj tmqyb msnnqf mhzc kydbva lrucncw fxc vzro