Parents: Help your child or teen

Online Volumes (Book Orders)
1,  Elements of Reason. 1996
1A. Pattern Based Reason  1995
1B. Math Curriculum Notes 1996
2. Three Skills for Algebra  1995
3.
_Why_Slopes_&_More_Math_1995

More Site Areas 
1.  Solving Linear Equations  2005
2.-Fractions-Rates-Proportns-Units-2006
3.  Algebra, Odds & Ends, HS level-2001
4.-Euclidean-Geometry/Complex No.s 
5.  Analytic Geometry/Functions 2006
6.  Number Theory. 2006-7
7.  Complex Numbers More 2001
8.  Calculus Introduction 2005
More Site Areas 
9   Real  Analysis 1995
10. Secondary IV? maths 2006-7
11. Math Education Essays  2006-7
12. LaTeX2HotEqn: 2004
13. Electric Circuits Etc  2007
14. Quebec Math Education 2004
15-Prequel-to-the-How-TOs-06-2008
How TOs/ Ref.-08- 2008
1. Arithmetic Reference
2. Algebra 
3. More Algebra 
4. Geometry  
5. More Geometry
6. Calculus
7. Logics in Maths


Employ an online or offline tutor at your own risk from 

AU:  tutorfinder.com.au
CDN :  findatutor.ca 
CDN: .i-tutor.ca
CDN: Montreal Tutors
NZ:   findatutor.co.nz
UK:   tutorhunt.com 
UK:  tutors4me.co.uk
USA:  wiziq.com
USA: ziizoo.com

YOU are better than YOU think. Show yourself  how:

      |      
//  _   _ \\
/\             /\
  <|  (o)   (o)   |> 
 \     | |      / 

 For better work & study skills, read logic chapters 1 to 5  in  Three Skills for Algebra. Sooner is better. Good luck.

 -/[]\- 
||
   / \_ 
 ||||||||||||||||||||||||||||


 Logic Mastery
 Amazing, Amusing, Amorous,  Delicious, Delightful, Edifying, Strengthening Elixir. 
It eases work & learning difficulties Makes the hard easier. Opens eyes. Leads to greater precision.
in reading and writing

Do not leave here without it -  Logic mastery  will develops critical thinking, improve reading and writing, and give a firmer base for work and studies at many levels. Good luck.

   |      
//  _   _ \\
/\             /\
<|   (o)   (o)  |> 
     | |     |
   \             /   
\    =   /

Caution: Site advice is approximately correct, for some circumstances, not all. Site How-TOs are logically developed, but not tried and tested. That leaves room for thought and refinement..

 -/[]\- 
||
  _ / \     
 ||||||||||||||||||||||||||||
 

After logic  (a) continue reading Three Skills for Algebra, chapters 8 to 14  and do so alongside site area on solving linear2007 Equations ; or (b) see this calculus starter lesson and Volume 3, Why Slopes  & More Math, chapters 2 to 6;


For online automated help in senior high school maths & calculus, visit  quickmath.com  For Automatic Calculus and Algebra Help with derivatives, integrals, graphs, linear equations, matrix algebra, visit calc101.com  With  overlap, each site quickmath & calc101offers a different range of services, some free, some not, all based on webmathematica. Good luck.


Explore collaborative whiteboards from groupboardtwiddla  or scriblink.


Decimal Expansions of Fractions

Finite or Infinite & Periodic

The long division process applied to a simple fraction

M
N

will terminate before or after the decimal point and give a whole number or a decimal fraction in decimal form if the simple fraction is equivalent to a decimal fraction. 

The long division will not terminate if the simple fraction

M
N

is not equivalent to a decimal fraction.  In this case,  long division in the first gives

M = k N +r 

where the remainder r is a whole number between 1 and N-1.  The remainder r will be nonzero as we are not in the decimal fraction case. Continuing the long division process to q decimal places after the decimal point gives 

10*M = kq*N +  rq

where the q-th remainder rq is a whole number between 0 and N and is kq is a  whole number..  

Now the infinite sequence of remainders takes values in the interval [1, N-1] of whole numbers - N-1 possible values in all. Therefore the remainders must repeat. If not, the interval [1, N-1] would have infinitely values.

Pigeon Hole Principle: Now the leading N remainders rq  where 1 < q < N sequence of remainders  takes values in the interval [1, N-1] of whole numbers - N-1 possible values in all. Therefore the remainders must repeat. If not, the interval [1, N-1] would include N distinct values.  

 It follows that the decimal expansion of M/N must start repeating on or before the N first place. So the period of the decimal expansion is N or less.

Check Logic later: Am I misleading myself in the above argument?

Now for each whole number q of decimal places, the equation 

10*M = kq*N +  rq

implies 

M
---
N
 =  kq
-----

10
+ rq
-----

10

where rq is in the interval [1,N-1] repeats and eventually has period P in q, that is,   rq+P =  rq for q sufficiently large, and where km for m > q agrees with kq to q decimal places.  Therefore,

M
N

has a periodic, non-terminating decimal expansion

 aTaT-1 ....a1.b1b2b3b4b5b.... 

in which the first q decimal places are provided by the decimal fraction 

kq
-----

10

We assume that a non-terminating decimal expansion may be associated with a single point on a coordinate (half) line:

A Cauchy sequence f(n)  has the following decimal property: For each whole number k, there is a whole number N with the following property: all terms in the sequence after the first N-1 agree with each other to at least k decimal places. This property allows us to define and compute in principle an infinite decimal expansion. This expansion is assumed to define a unique real number: the limit L of the Cauchy sequence.

The limit of a repeating non-terminating, infinite decimal expansion is given by a simple fraction. For a proof, study the geometric series. 

Exercise: If two non-terminating periodic decimals differ at the k-th place in their expansion then the two decimals converge to different limits. Explain or see why.

 

www.whyslopes.com
Number Theory

Back ] Up ] Next ]

Start of Number Theory

Origins of Counting or Tallying
Adding Wholes
Multipling Wholes
Distributive Law  Preamble
Distributive Law for Wholes
Consequences
More Consequences
What is a Fraction
Compound Fractions

Number Theory
Continued


Decimal Place Value
Place Value Reinforcement
Comparison Method
Addition Method
Subtraction Methods
Multiplication Methods
Division Methods
Remainder Arithmetic I
Primes & Composites
Primes Factorization Theorem
Primes & Composites
Prime Factorization Aids
Prime Factorization Examples
Counting  Whole No.  Factors
Arithmetic Videos
Square Roots  & Primes
Long Division Continued
Fractions & Decimals
Fractions as Decimals
1 = 0.999 Recurring
Infinite Decimals Expansion Arithmetic
Ratio of Simple Fractions
Ratio of Decimal Fractions
Unsigned Reals Numbers
Signed Coordinates
Plane Vectors
Horizontal Vectors
Adding Vector Multiplies
Adding Signed Numbers
Multiplying Signed Numbers
Distributive Law for Reals
Real Numbers Axioms
Remainder Arithmetic II

Related Site Pages:

For online automated help in senior high school maths & calculus, visit  quickmath.com  For Automatic Calculus and Algebra Help with derivatives, integrals, graphs, linear equations, matrix algebra, visit calc101.com  With  overlap, each site quickmath & calc101offers a different range of services, some free, some not, all based on webmathematica. Good luck

Food for thought: Try the Twiddla Whiteboard. In principle, it  allows to people to draw and chat together online on a copy of this webpage or a clean sheet. The chat may be via text or audio.  Visit www.twiddla.com to set up whiteboards to work with the webpage of your choice..

 

[Page Top] Back ] Area Intro ] Next ] 
If you find an error, please  email  its description and  web page location (URL). Thxs.

Wordy Site Tour:  Not too Bad Vol 2. Foreword 1A Foreword2  Logic Puzzles,  
What is a Variable
  Calculus Starter Guide  Vol 1 Foreword,  
 
 
Favourite Sites
The World Clock - Time Zones Around the World  
 BBC News  and mathematics portion of  English National Curriculum  

All trademarks and copyrights on this page are owned by their respective owners.
Copyright to comments & contributions are owned by the Poster. 
The Rest © 1995 onward by site author,   Alan Selby
All Rights Reserved.