Appetizers and Lessons for Mathematics and Reason (www.whyslopes.com)
a calculus, preparation for calculus and math ed reform website, etc.

Online Volumes (Book Orders)
1,  Elements of Reason.
1A. Pattern Based Reason 
1B. Math Curriculum Notes
2. Three Skills for Algebra
3. Why Slopes & More Math

Mathematics Course Designers: LAMP offers food for thought.
More Site Areas 
1. Help Your Child or Teen Learn 
2. Solving Linear Equations
3. Fractions Ratios Rates Proportions & Units
4. Euclidean Geometry
5. Analytic Geometry/Functions 
6. Number Theory
7. More Calculus
More Site Areas 
8. Complex Numbers 
9. Qc Maths  Education  
10. Secondary IV(?) maths
11. Real  Analysis 
12. LaTeX2HotEqn:
13. Electric Circuits Etc  
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15. Algebra, Odds & Ends, Etc
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16. Math Education Essays
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20. Statistics Useful, or Not. 

||Définition d'une variable || Algèbre || Arithmetique || Logique ||La raison basée sur les règles et modelés||
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YOU are better than YOU think. Show yourself  how:  

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Read  logic chapters 1 to 5  in online volume Three Skills for Algebra  for greater skills & confidence in  work 
and study

Learn to read notes and textbooks like a lawyer, so that no nuance, no subtlety and no clause escapes your attention.

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 Logic chapters 1 to 5  re- appear not in sequence, as is or longer,  in  Volume 1A,  Pattern Based Reason, Bon Appetite.

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

Logic mastery makes the hard, easier. Logic mastery  leads to better, stronger and richer comprehension.  Logic mastery  improves reading and writing.  Logic mastery ease learning difficulties.  Logic mastery gives a headstart.  In sum, logic mastery  will develops critical thinking, improve reading and writing, and give a firmer base for work and studies at many levels. Good luck.


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

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Caution: Site advice is approximately correct, for some circumstances, not all. That leaves room for thought

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What may be learnt and when depends on how skills and concepts are developed. Making the hard easier and clearer will allow earlier & richer development of skills and concepts.


 

Equi-Sized Groups - Repeated Addition,
Multiplication and its Properties

How many elements are there in a finite set of  equi-sized groups?

Product Rule - Counting or Denoting How Many in Equal-Sized Groups

The number of elements in M groups, each of size N, gives a count denoted by M*N and called M times N or the product of M and N. 

For example 1 times N is N and 2*N is N +N, 3*N is N+N+N.  We will see later how to denote counts by decimals and how to mutliply decimals. 

Commutative Law for Multiplication

Geometric Reason for 5 x 3  = 3 x 5

5  columns (groups) of three pluses
+ + + + +
+ + + + +
+ + + + +

can also be viewed of 3 rows (groups) of 5 pluses without losing or gaining pluses - the tally marks. Therefore  5*3 = 3*5 = two ways of counting them.  Here we use the assumption that any  two ways of counting the same set of elements must yield the same number. 

Geometric Reason for MxN = N x M

Now if M groups, each of size of N,  are stacked in N equi-height columns, where each group element occupies a single square in that column, then all squares being the same size, we obtain a rectangle.  Now we divide the total number present into N rows (groups) of M elements each. So that implies the total count or tally initially given by M*N is also given by N*M. 

The foregoing as is or recast implies the commutative law of multiplication namely

Commutative Law:  N*M =M*N whenever M and N are whole numbers. 

Students of pure mathematics can recast the foregoing into set theory form where the number of elements in the Cartesian product A x B of two sets is M*N if A and B have M and N elements, respectively. The number of elements in the Cartesian product defines M*N.

Associative Law for Multiplication

In general, for any three whole numbers M, N and P, 

 N(MP) = (NM)P)

Proof: Suppose we divide a set of cubes T = N(MP) cubes into  N one-cube high layers of M by P cubes, and stack the layers. The result is a rectangular box of cubes  N cubes high, M cubes wide and P cubes long.  Now we may recount the by viewing the box as   NM columns, each  P cubes long.. That yield T = (NM)P as well.  

Corollary:    N(MP) = (NM)P =  (MN)P = M(NP) = P(MN) = (PM)N 

We can take the value of NMP to be the common value of the six ways to compute the number of small boxes (cubes with sides of unit length) in a larger box with dimensions N units, M units and P units. 

Remark. In more advanced mathematics, the foregoing may be rewritten algebraically to give a formal proof. By mathematically induction, we may argue that a product of r whole number factors yields a single  result independent of the order and grouping. Thus grouping and regrouping view as different ways to count a r-dimensional hyper-box  implies order of multiplication does not affect results.

Consequences of Associative Law:  

In our discussion of decimal methods below, we will need the property that 

 (a 10m) x (b 10n) =  (ab) 10m+n

That follows as  (a 10m) x (b 10n)  

=  (a x 10m) x (b 10n) due to a change in notation
a x (10m x (b 10n)) due to a 1st use of associative law
a x (b x (10m x  10n)) due to a 2nd use of associative law or six ways to compute the product 10m x (b 10n)
a x (b x (10m+n))  as 10m+n =10m x  10n
(a b) x 10m+n  due to a 3rd use of associative law
= (a b) x 10m+n  due to a change in notation

Note: Some authors might mention the commutative law in going from one way to compute the product 10m x (b 10n)to another.

 

www.whyslopes.com
Number Theory

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
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
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..

 



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a 1983 McGill. Ph. D. in mathematics
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