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Multiplicative inverse

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Name

Description

Asks students to compute the multiplicative inverse of $a$ in $\mathbb{Z}_n$ where $n$ is an odd number between 31 and 61 and $a$ is an integer coprime to $n$ that lies between $n/4$ and $3n/4$ .

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Metadata

Author

Maura Paterson

Project

Maura's workspace

Licence

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Ability levels

England schools
- Primary school
- Key Stage 1
- Key Stage 2
- Key Stage 3
- Key Stage 4 / GCSE
- A-Level
England university
- Transition to university
- Stage 1
- Stage 2
- Stage 3
- Postgraduate
Scotland schools
- 1st Level
- 2nd Level
- 3rd/4th Level
- National 4 & 5
- Higher
- Advanced Higher

Taxonomy: mathcentre

mathcentre's taxonomy.

1 - Numbers and Computation

1.1 - Number Concepts

1.1.1 - Natural

1.1.2 - Integers

1.1.3 - Rational

1.1.4 - Irrational

1.1.5 - Algebraic

1.1.6 - Real

1.1.7 - Complex

1.1.8 - Famous Numbers

1.1.8.1 - 0

1.1.8.2 - pi

1.1.8.3 - e

1.1.8.4 - i

1.1.8.5 - Golden Mean

1.1.9 - Symbols, constants

1.2 - Arithmetic

1.2.1 - Operations

1.2.1.1 - Addition

1.2.1.2 - Subtraction

1.2.1.3 - Multiplication

1.2.1.4 - Division

1.2.1.5 - Roots

1.2.1.6 - Factorials

1.2.1.7 - Factoring

1.2.1.8 - Properties of Operations

1.2.1.9 - Estimation

1.2.2 - Fractions

1.2.2.1 - Addition

1.2.2.2 - Subtraction

1.2.2.3 - Multiplication

1.2.2.4 - Division

1.2.2.5 - Ratio and Proportion

1.2.2.6 - Equivalent Fractions

1.2.3 - Decimals

1.2.3.1 - Addition

1.2.3.2 - Subtraction

1.2.3.3 - Multiplication

1.2.3.4 - Division

1.2.3.5 - Percents

1.2.4 - Comparison of numbers

1.2.5 - Exponents

1.2.5.1 - Multiplication

1.2.5.2 - Division

1.2.5.3 - Powers

1.2.5.4 - Integer Exponents

1.2.5.5 - Rational Exponents

1.2.6 - Logarithms

1.2.6.1 - Addition

1.2.6.2 - Subtraction

1.2.6.3 - Multiplication

1.2.6.4 - Natural logarithms

1.2.6.5 - Change of base

1.3 - Patterns and Sequences

1.3.1 - Number Patterns

1.3.2 - Fibonacci Sequence

1.3.3 - Arithmetic Sequence

1.3.4 - Geometric Sequence

1.4 - Measurement

1.4.1 - Units of Measurement

1.4.1.1 - Metric System

1.4.1.2 - Standard Units

1.4.1.3 - Nonstandard Units

1.4.2 - Linear Measure

1.4.2.1 - Distance

1.4.2.2 - Circumference

1.4.2.3 - Perimeter

1.4.3 - Area

1.4.3.1 - Area of Polygons

1.4.3.2 - Area of Circles

1.4.3.3 - Surface Area

1.4.3.4 - Nonstandard Shapes

1.4.4 - Volume

1.4.5 - Weight and Mass

1.4.6 - Temperature

1.4.7 - Time

1.4.8 - Speed

1.4.9 - Money

1.4.10 - Scale

2 - Logic and Foundations

2.1 - Logic

2.1.1 - Logic

2.1.2 - Propositional and Predicate Logic

2.1.3 - Methods of Proof

2.2 - Set Theory

2.2.1 - Sets and Set Operations

2.2.2 - Relations and Functions

2.2.3 - Cardinality

2.2.4 - Axiom of Choice

2.3 - Computability and Decidability

2.4 - Model Theory

3 - Algebra and Number Theory

3.1 - Algebra

3.1.1 - Graphing Techniques

3.1.2 - Algebraic Manipulation

3.1.2.1 - Collecting like terms

3.1.2.2 - Rules of indices for single term expressions

3.1.2.2.1 - Surds

3.1.2.3 - Polynomial expressions

3.1.2.3.1 - Multiplying out brackets

3.1.2.3.1.1 - Multiplying a single-term expression and bracket

3.1.2.3.1.2 - Multiplying two brackets

3.1.2.3.1.3 - Pure powers

3.1.2.3.1.4 - The difference of two squares

3.1.2.3.1.5 - Multiple brackets

3.1.2.3.2 - Factoring polynomials

3.1.2.3.2.1 - Single term common factor

3.1.2.3.2.2 - Quadratic expressions

3.1.2.3.2.3 - Higher powers

3.1.2.3.2.4 - Multiple variable expressions

3.1.2.4 - Algebraic fractions

3.1.2.4.1 - Cancelling

3.1.2.4.1.1 - Cancelling fractions involving factorising

3.1.2.4.2 - Multiplying by -1

3.1.2.4.3 - Adding and subtracting algebraic fractions

3.1.2.4.4 - Multiplying and dividing algebraic fractions

3.1.2.4.5 - Partial fractions

3.1.2.4.6 - Rationalizing surd expressions

3.1.2.5 - Completing the square of a quadratic expression

3.1.2.6 - Rearranging equations

3.1.2.6.1 - Substituting from one formula into another

3.1.2.6.2 - Making a specified letter the subject of a formula

3.1.2.6.3 - Substitution

3.1.2.7 - De-nesting surds

3.1.3 - Functions

3.1.3.1 - Linear

3.1.3.2 - Quadratic

3.1.3.3 - Polynomial

3.1.3.4 - Rational

3.1.3.5 - Exponential

3.1.3.6 - Logarithmic

3.1.3.7 - Piece-wise

3.1.3.8 - Step

3.1.3.9 - Hyperbolics

3.1.3.9.1 - Hyperbolic functions

3.1.3.9.2 - Inverse hyperbolic functions

3.1.3.9.3 - Hyperbolic identities

3.1.4 - Equations

3.1.4.1 - Linear

3.1.4.2 - Quadratic

3.1.4.3 - Polynomial

3.1.4.4 - Rational

3.1.4.5 - Exponential

3.1.4.6 - Logarithmic

3.1.4.7 - Systems

3.1.5 - Inequalities

3.1.6 - Matrices

3.1.7 - Sequences and Series

3.1.8 - Algebraic Proof

3.2 - Linear Algebra

3.2.1 - Systems of Linear Equations

3.2.2 - Matrix algebra

3.2.3 - Vectors in R3

3.2.4 - Vector Spaces

3.2.5 - Linear Transformations

3.2.6 - Eigenvalues and Eigenvectors

3.2.7 - Inner Product Spaces

3.3 - Abstract Algebra

3.3.1 - Groups

3.3.2 - Rings and Ideals

3.3.3 - Fields

3.3.4 - Galois Theory

3.3.5 - Multilinear Algebra

3.4 - Number Theory

3.4.1 - Integers

3.4.2 - Primes

3.4.2.1 - Divisibility

3.4.2.2 - Factorization

3.4.2.3 - Distributions of Primes

3.4.3 - Congruences

3.4.4 - Diophantine Equations

3.4.5 - Irrational Numbers

3.4.6 - Famous Problems

3.4.7 - Coding Theory

3.4.8 - Cryptography

3.5 - Category Theory

3.6 - K-Theory

3.7 - Homological Algebra

3.8 - Modular Arithmetic

4 - Discrete Mathematics

4.1 - Cellular Automata

4.2 - Combinatorics

4.2.1 - Combinations

4.2.2 - Permutations

4.3 - Game Theory

4.4 - Algorithms

4.5 - Recursion

4.6 - Graph Theory

4.7 - Linear Programming

4.8 - Order and Lattices

4.9 - Theory of Computation

4.10 - Chaos

5 - Geometry and Topology

5.1 - Geometric Proof

5.2 - Plane Geometry

5.2.1 - Measurement

5.2.2 - Lines and Planes

5.2.3 - Angles

5.2.4 - Triangles

5.2.4.1 - Properties

5.2.4.2 - Congruence

5.2.4.3 - Similarity

5.2.4.4 - Pythagorean Theorem

5.2.5 - Polygons

5.2.5.1 - Properties

5.2.5.2 - Regular

5.2.5.3 - Irregular

5.2.5.4 - Congruence

5.2.5.5 - Similarity

5.2.6 - Circles

5.2.7 - Patterns

5.2.7.1 - Geometric Patterns

5.2.7.2 - Tilings and Tessellations

5.2.7.3 - Symmetry

5.2.7.4 - Golden Ratio

5.2.8 - Transformations

5.2.8.1 - Translation

5.2.8.2 - Rotation

5.2.8.3 - Reflection

5.2.8.4 - Scaling

5.3 - Solid Geometry

5.3.1 - Dihedral Angles

5.3.2 - Spheres

5.3.3 - Cones

5.3.4 - Cylinders

5.3.5 - Pyramids

5.3.6 - Prisms

5.3.7 - Polyhedra

5.4 - Analytic Geometry

5.4.1 - Cartesian Coordinates

5.4.2 - Lines

5.4.3 - Circles

5.4.4 - Planes

5.4.5 - Conics

5.4.6 - Polar Coordinates

5.4.7 - Parametric Curves

5.4.8 - Surfaces

5.4.9 - Distance Formula

5.5 - Projective Geometry

5.6 - Differential Geometry

5.7 - Algebraic Geometry

5.8 - Topology

5.8.1 - Point Set Topology

5.8.2 - General Topology

5.8.3 - Differential Topology

5.8.4 - Algebraic Topology

5.9 - Trigonometry

5.9.1 - Angles

5.9.2 - Trigonometric Functions

5.9.3 - Inverse Trigonometric Functions

5.9.4 - Trigonometric Identities

5.9.5 - Trigonometric Equations

5.9.6 - Roots of Unity

5.9.7 - Spherical Trigonometry

5.10 - Fractal Geometry

6 - Calculus

6.1 - Single Variable

6.1.1 - Functions

6.1.2 - Limits

6.1.3 - Continuity

6.1.4 - Differentiation

6.1.5 - Integration

6.1.6 - Series

6.2 - Several Variables

6.2.1 - Functions of Several Variables

6.2.2 - Limits

6.2.3 - Continuity

6.2.4 - Partial Derivatives

6.2.5 - Multiple integrals

6.2.6 - Taylor Series

6.3 - Advanced Calculus

6.3.1 - Vector Valued Functions

6.3.2 - Line Integrals

6.3.3 - Surface Integrals

6.3.4 - Stokes Theorem

6.3.5 - Curvilinear Coordinates

6.3.6 - Linear spaces

6.3.7 - Fourier Series

6.3.8 - Orthogonal Functions

6.4 - Tensor Calculus

6.5 - Calculus of Variations

6.6 - Operational Calculus

7 - Analysis

7.1 - Real Analysis

7.1.1 - Metric Spaces

7.1.2 - Convergence

7.1.3 - Continuity

7.1.4 - Differentiation

7.1.5 - Integration

7.1.6 - Measure Theory

7.2 - Complex Analysis

7.2.1 - Convergence

7.2.2 - Infinite Series

7.2.3 - Analytic Functions

7.2.4 - Integration

7.2.5 - Contour Integrals

7.2.6 - Conformal Mappings

7.2.7 - Several Complex Variables

7.3 - Numerical Analysis

7.3.1 - Computer Arithmetic

7.3.2 - Solutions of Equations

7.3.3 - Solutions of Systems

7.3.4 - Interpolation

7.3.5 - Numerical Differentiation

7.3.6 - Numerical Integration

7.3.7 - Numerical Solutions of ODEs

7.3.8 - Numerical Solutions of PDEs

7.4 - Integral Transformations

7.4.1 - Fourier Transforms

7.4.2 - Laplace Transforms

7.4.3 - Hankel Transforms

7.4.4 - Wavelets

7.4.5 - Other Transforms

7.5 - Signal Analysis

7.5.1 - Sampling Theory

7.5.2 - Filters

7.5.3 - Noise

7.5.4 - Data Compression

7.5.5 - Image Processing

7.6 - Functional Analysis

7.6.1 - Hilbert Spaces

7.6.2 - Banach Spaces

7.6.3 - Topological Spaces

7.6.4 - Locally Convex Spaces

7.6.5 - Bounded Operators

7.6.6 - Spectral Theorem

7.6.7 - Unbounded Operators

7.7 - Harmonic Analysis

7.8 - Global Analysis

8 - Differential and Difference Equations

8.1 - Ordinary Differential Equations

8.1.1 - First Order

8.1.2 - Second Order

8.1.3 - Linear Oscillations

8.1.4 - Nonlinear Oscillations

8.1.5 - Systems of Differential Equations

8.1.6 - Sturm Liouville Problems

8.1.7 - Special Functions

8.1.8 - Power Series Methods

8.1.9 - Laplace Transforms

8.2 - Partial Differential Equations

8.2.1 - First Order

8.2.2 - Elliptic

8.2.3 - Parabolic

8.2.4 - Hyperbolic

8.2.5 - Integral Transforms

8.2.6 - Integral Equations

8.2.7 - Potential Theory

8.2.8 - Nonlinear Equations

8.2.9 - Symmetries and Integrability

8.3 - Difference Equations

8.3.1 - First Order

8.3.2 - Second Order

8.3.3 - Linear Systems

8.3.4 - Z Transforms

8.3.5 - Orthogonal Polynomials

8.4 - Dynamical Systems

8.4.1 - 1D Maps

8.4.2 - 2D Maps

8.4.3 - Lyapunov Exponents

8.4.4 - Bifurcations

8.4.5 - Fractals

8.4.6 - Differentiable Dynamics

8.4.7 - Conservative Dynamics

8.4.8 - Chaos

8.4.9 - Complex Dynamical Systems

9 - Statistics and Probability

9.1. - Data Collection

9.1.1. - Experimental Design

9.1.2. - Sampling and Surveys

9.1.3. - Data and Measurement Issues

9.2. - Data Summary and Presentation

9.2.1. - Summary Statistics

9.2.1.1. - Measures of Central Tendency

9.2.1.2. - Measures of Spread

9.2.2. - Data Representation

9.2.2.1. - Graphs and Plots

9.2.2.2. - Tables

9.3. - Statistical Inference and Techniques

9.3.1. - Sampling Distributions

9.3.2. - Regression and Correlation

9.3.3. - Confidence Intervals

9.3.4. - Hypothesis Tests

9.3.5. - Statistical Quality Control

9.3.6. - Non-parametric Techniques

9.3.7. - Multivariate Techniques

9.3.8. - Survival Analysis

9.3.9. - Bayesian Statistics

9.4. - Probability

9.4.3 - Limit Theorems

9.4.3.1 - Central Limit Theorem

9.4.3.2 - Law of Large Numbers

9.4.5 - Stochastic Processes

9.4.5.1 - Brownian Motion

9.4.5.2 - Markov Chains

9.4.5.3 - Queuing Theory

9.4.6 - Probability Measures

9.4.7 - Simulation

9.4.1. - Elementary Probability

9.4.1.1. - Sample Space and Events

9.4.1.2. - General Rules

9.4.1.3. - Combinations and Permutations

9.4.1.4. - Random Variables

9.4.2. - Univariate Distributions

9.4.2.1. - Discrete Distributions

9.4.2.2. - Continuous Distributions

9.4.2.3. - Expected Value

9.4.4. - Multivariate Distributions

9.4.4.1 - Joint

9.4.4.2 - Conditional

9.4.4.3 - Expectations

10.0 - Applied Mathematics

10.1 - Mathematical Physics

10.2 - Mathematical Economics

10.3 - Mathematical Biology

10.4 - Mathematics for Business

10.5 - Engineering Mathematics

10.5.1 - Mathematics for Materials

10.6 - Mathematical Sociology

10.7 - Mathematics for Social Sciences

10.7.1 - Mathematics for Social Policy and Social Work

10.8 - Mathematics for Computer Science

10.9 - Mathematics for Humanities

10.9.1 - Mathematics for Art, Design and Communication

10.9.2 - Mathematics for Built Environment

10.9.3 - Mathematics for History, Classics and Archaeology

10.9.4 - Mathematics for Law

10.9.5 - Mathematics for Performing Arts

10.9.6 - Mathematics for Education

10.9.7 - Mathematics for Languages, Linguistics and Area Studies

10.9.7.1 - Mathematics for English

10.9.8 - Mathematics for Philosophical and Religious Studies

10.10 - Consumer Mathematics

10.11 - Mathematics for Economics

10.12 - Mathematics for Life Sciences

10.12.1 - Mathematics for Geography, Earth and Environmental Sciences

10.12.2 - Mathematics for Bioscience

10.12.3 - Mathematics for Health Sciences and Practice

10.12.4 - Mathematics for Medicine, Dentistry and Veterinary Medicine

10.13 - Mathematics for Psychology

10.14 - Mathematics for Physical Sciences

10.15 - Mathematics for Sociology, Anthropology and Politics

10.16 - Mathematics for Hospitality, Leisure, Sport and Tourism

11.0 - Mathematics History

11.1 - General

11.2 - Famous Problems

11.3 - Biographies of Mathematicians

12.0 - Mathematical Education

Taxonomy: Kind of activity

1 - Create

1.1 - Give an example

1.2 - Give a starting point

1.3 - Give an argument

2 - Evaluate

2.1 - Make a decision

2.2 - Classify an object

3 - Analyze

3.1 - Interpret a situation

3.2 - Select from a list of options

3.3 - Identify an error

4 - Apply

4.1 - Use formulas

4.2 - Perform a routine calculation or algorithm

4.3 - Apply an algorithm

5 - Understand

5.1 - Use an appropriate formula

5.2 - Identify a component

6 - Remember

6.1 - Recall a fact

Taxonomy: Context

1 - Mathematics

1.1 - Pure

1.2 - Applied

1.3 - For...

1.3.1 - Accountancy

1.3.2 - Business

1.3.3 - Psychology

1.3.4 - Science

1.3.4.1 - Biomedicine

1.3.4.2 - Chemistry

1.3.4.3 - Biology

2 - Statistics

2.1 - Bayesian

2.2 - Frequentist

3 - Physics

3.1 - Theoretical

4 - Engineering

4.1 - Civil

4.2 - Electrical

4.3 - Chemical

5 - Chemistry

Contributors

Maura Paterson

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Maura Paterson

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Maura Paterson 1 year, 6 months ago

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Maura Paterson 1 year, 7 months ago

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Question statement

Determine the inverse of $\var{a}\pmod{\var{n}}$ .

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			Name	Type	Generated Value

n	integer	61
a	integer	20
calcs	list	Nested 3×7 list
k	number	2
tmatrix	matrix	matrix([0,1,-3])
inverse	number	58
smatrix	matrix	matrix([1,0,1])

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Generated value: `integer`

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a
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inverse

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Ask the student a question, and give any hints about how they should answer this part.

(Express your answer as an integer between $0$ and $\var{n-1}$ inclusive.)

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English (Plain) No thousands separator; dot for decimal point.
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SI (French) Spaces separate thousands; comma for decimal point.
Continental Dots separate thousands; comma for decimal point.
Continental (Plain) No thousands separator; comma for decimal point.
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Indian Commas separate groups; rightmost group is 3 digits, other groups 2 digits; dot for decimal point.
Scientific A significand followed by the letter 'e' and an integer exponent.

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We observe that {a} is coprime to {n} and thus has a multiplicative inverse. We use the Extended Euclidean Algorithm to determine that $1=\var{smatrix[0][k]}\cdot\var{n}+\var{tmatrix[0][k]}\cdot\var{a}$ , and so the inverse of {a} is $\var{mod(tmatrix[0][k],n)}$ .

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This question is used in the following exams:

testtest by Maura Paterson in Maura's workspace.
NTC Assignment 1 Quiz by Maura Paterson in Maura's workspace.
My first exam by Øystein Skartsæterhagen in Øystein's workspace.

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Multiplicative inverse

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Taxonomy: mathcentre

Taxonomy: Kind of activity

Taxonomy: Context

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Maura Paterson 1 year, 6 months ago

Maura Paterson 1 year, 7 months ago

Maura Paterson 1 year, 7 months ago

Error in variable testing condition

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Generated value: `integer`