2. Multiplying and dividing

2020 ◽  
pp. 14-37
Author(s):  
Robin Wilson
Keyword(s):  
Number Theory ◽  
Greatest Common Divisor ◽  
Common Multiple ◽  
Least Common Multiple ◽  
Euclid’S Algorithm ◽  
Division Rule ◽  
Perfect Squares ◽  
Euclid's Algorithm

‘Multiplying and dividing’ looks at multiples and divisors, focusing on the least common multiple and greatest common divisor of two numbers. We use Euclid’s algorithm as a method for computing the greatest common divisor of two numbers by using the division rule repeatedly. Perfect squares (integers that are the product of two equal integers) feature throughout number theory. Tests are given for divisibility by certain small numbers. An ancient method called ‘casting out nines’, was developed in India in around the year 1000, based on the argument that a number and its digital sum leave the same remainder when divided by 9. We can still use this method to verify the accuracy (or otherwise) of arithmetical calculations.

Euclid's Algorithm Revisited

1967 ◽  
Vol 60 (4) ◽  
pp. 358
Author(s):  
B. L. Foster
Keyword(s):  
Automatic Machine ◽  
Greatest Common Divisor ◽  
Machine Computation ◽  
Euclid’S Algorithm ◽  
Integer Division ◽  
Euclid's Algorithm

Since integer division reduces to repeated subtraction, Euclid's algorithm for finding the greatest common divisor may be recast in terms of subtraction. This is done, for example, in Trakhtenbrot,1 for automatic machine computation.

MORE ON A CERTAIN ARITHMETICAL DETERMINANT

2017 ◽  
Vol 97 (1) ◽  
pp. 15-25 ◽  
Author(s):  
ZONGBING LIN ◽  
SIAO HONG
Keyword(s):  
Linear Algebra ◽  
Acta Math ◽  
Arithmetical Function ◽  
Greatest Common Divisor ◽  
Multiplicative Functions ◽  
Common Multiple ◽  
Least Common Multiple ◽  
Mobius Function ◽  
Dirichlet Convolution ◽  
Positive Integers

Let $n\geq 1$ be an integer and $f$ be an arithmetical function. Let $S=\{x_{1},\ldots ,x_{n}\}$ be a set of $n$ distinct positive integers with the property that $d\in S$ if $x\in S$ and $d|x$. Then $\min (S)=1$. Let $(f(S))=(f(\gcd (x_{i},x_{j})))$ and $(f[S])=(f(\text{lcm}(x_{i},x_{j})))$ denote the $n\times n$ matrices whose $(i,j)$-entries are $f$ evaluated at the greatest common divisor of $x_{i}$ and $x_{j}$ and the least common multiple of $x_{i}$ and $x_{j}$, respectively. In 1875, Smith [‘On the value of a certain arithmetical determinant’, Proc. Lond. Math. Soc. 7 (1875–76), 208–212] showed that $\det (f(S))=\prod _{l=1}^{n}(f\ast \unicode[STIX]{x1D707})(x_{l})$, where $f\ast \unicode[STIX]{x1D707}$ is the Dirichlet convolution of $f$ and the Möbius function $\unicode[STIX]{x1D707}$. Bourque and Ligh [‘Matrices associated with classes of multiplicative functions’, Linear Algebra Appl. 216 (1995), 267–275] computed the determinant $\det (f[S])$ if $f$ is multiplicative and, Hong, Hu and Lin [‘On a certain arithmetical determinant’, Acta Math. Hungar. 150 (2016), 372–382] gave formulae for the determinants $\det (f(S\setminus \{1\}))$ and $\det (f[S\setminus \{1\}])$. In this paper, we evaluate the determinant $\det (f(S\setminus \{x_{t}\}))$ for any integer $t$ with $1\leq t\leq n$ and also the determinant $\det (f[S\setminus \{x_{t}\}])$ if $f$ is multiplicative.

scholarly journals Partial Correctness of GCD Algorithm

2018 ◽  
Vol 26 (2) ◽  
pp. 165-173
Author(s):  
Ievgen Ivanov ◽  
Artur Korniłowicz ◽  
Mykola Nikitchenko
Keyword(s):  
Greatest Common Divisor ◽  
Hoare Logic ◽  
Natural Numbers ◽  
Inference System ◽  
Partial Correctness ◽  
Euclid’S Algorithm ◽  
System 2 ◽  
Euclid's Algorithm ◽  
Complex Valued

Summary In this paper we present a formalization in the Mizar system [2, 1] of the correctness of the subtraction-based version of Euclid’s algorithm computing the greatest common divisor of natural numbers. The algorithm is written in terms of simple-named complex-valued nominative data [11, 4]. The validity of the algorithm is presented in terms of semantic Floyd-Hoare triples over such data [7]. Proofs of the correctness are based on an inference system for an extended Floyd-Hoare logic with partial pre- and post-conditions [8, 10, 5, 3].

scholarly journals Computational Thinking in Mathematics and Computer Science: What Programming Does to Your Head

2021 ◽  
Vol 11 (1) ◽  
pp. 346-363
Author(s):  
Al Cuoco ◽  
Paul Goldenberg
Keyword(s):  
Computer Science ◽  
Classical Result ◽  
Computational Thinking ◽  
Computer Programs ◽  
The Other ◽  
Greatest Common Divisor ◽  
Euclid’S Algorithm ◽  
And Mathematics ◽  
Euclid's Algorithm

How you think about a phenomenon certainly influences how you create a program to model it. The main point of this essay is that the influence goes both ways: creating programs influences how you think. The programs we are talking about are not just the ones we write for a computer. Programs can be implemented on a computer or with physical devices or in your mind. The implementation can bring your ideas to life. Often, though, the implementation and the ideas develop in tandem, each acting as a mirror on the other. We describe an example of how programming and mathematics come together to inform and shape our interpretation of a classical result in mathematics: Euclid's algorithm that finds the greatest common divisor of two integers.

On the divisibility among power GCD and power LCM matrices on gcd-closed sets

2021 ◽  
pp. 1-12
Author(s):  
Guangyan Zhu
Keyword(s):  
Greatest Common Divisor ◽  
Text Entry ◽  
Common Multiple ◽  
Least Common Multiple ◽  
Closed Set ◽  
Closed Sets ◽  
Matrix Formula ◽  
Power Matrix ◽  
Positive Integers

Let [Formula: see text] and [Formula: see text] be positive integers and let [Formula: see text] be a set of [Formula: see text] distinct positive integers. For [Formula: see text], one defines [Formula: see text]. We denote by [Formula: see text] (respectively, [Formula: see text]) the [Formula: see text] matrix having the [Formula: see text]th power of the greatest common divisor (respectively, the least common multiple) of [Formula: see text] and [Formula: see text] as its [Formula: see text]-entry. In this paper, we show that for arbitrary positive integers [Formula: see text] and [Formula: see text] with [Formula: see text], the [Formula: see text]th power matrices [Formula: see text] and [Formula: see text] are both divisible by the [Formula: see text]th power matrix [Formula: see text] if [Formula: see text] is a gcd-closed set (i.e. [Formula: see text] for all integers [Formula: see text] and [Formula: see text] with [Formula: see text]) such that [Formula: see text]. This confirms two conjectures of Shaofang Hong proposed in 2008.

Ancient Algorithms

2020 ◽  
pp. 9-24
Author(s):  
Chris Bleakley
Keyword(s):  
Prime Numbers ◽  
Pythagorean Theorem ◽  
Greatest Common Divisor ◽  
Stepping Stones ◽  
Euclid’S Algorithm ◽  
Ancient Mesopotamia ◽  
Euclid's Algorithm ◽  
Modern Cryptography

Chapter 1 traces the origins of algorithms from ancient Mesopotamia to Greece in the 2th century BC. The oldest known algorithms were inscribed on clay tablets by the Babylonians more than 4,000 years ago. The clay tablets document algorithms ranging from geometry to accountancy. One tablet in particular - YBC 7289 - indicates knowledge of the Pythagorean Theorem thousands of years before its supposed invention by the ancient Greeks. The Greeks made other advances in algorithms. Euclid’s algorithm determines the greatest common divisor of two numbers. The Sieve of Eratosthenes finds prime numbers. Both algorithms proved to be important stepping stones to modern cryptography - the mathematics of secret messages.

scholarly journals The Effect of Guided Inquiry Learning Model to the Metacognitive Ability of Primary School Students

2020 ◽  
Vol 8 (1) ◽  
pp. 37
Author(s):  
Intan Dwi Hastuti ◽  
Yuni Mariyati ◽  
S. Sutarto ◽  
Chairun Nasirin
Keyword(s):  
Primary School ◽  
Inquiry Learning ◽  
Learning Model ◽  
Greatest Common Divisor ◽  
Guided Inquiry ◽  
Primary School Students ◽  
School Students ◽  
Common Multiple ◽  
Least Common Multiple ◽  
Metacognitive Ability

This study aimed at analyzing the effect of guided inquiry learning to the metacognitive ability of primary school students on the material of Least Common Multiple (KPK) and Greatest Common Divisor (FPB). The type of study was a mixed-method using quantitative and qualitative methods. There were 55 students of 4th grade used as the subjects of study. Two learning models were compared, namely guided inquiry learning model and conventional learning model. The students’ metacognitive ability was measured by means of problem-solving test on the material of Least Common Multiple (KPK) and Greatest Common Divisor (FPB). The quantitative analysis data used descriptive and inferential statistical tests. According to the results of data analysis, it was discovered that the t-test of sig (2-tailed) from the independent samples t-test of post-test was 0,00 (p = <0,05); this indicated that there was a significant difference on it. This showed that there was a difference of students’ metacognitive ability for both classes in solving the problems of Least Common Multiple (KPK) and Greatest Common Divisor (FPB) after the guided inquiry learning was implemented. Consequently, it can be concluded that there is a significant effect on the implementation of guided inquiry learning model to improve the students’ metacognitive ability in solving the material problems of Least Common Multiple (KPK) and Greatest Common Divisor (FPB).

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