Math 6 Honors (Period 6 and 7)

Adding Integers 11-2

Rules: The sum of two positive integers is a positive integer.
The sum of two negative integers is a negative integer.

So- if the two numbers have the same sign, use their sign and just add the numbers.

-15 + -13 = - 28

-10 + -4 = -14

Rules: The sum of a positive integer and a negative integer is :

POSITIVE… IF the positive number has a greater absolute value

NEGATIVE… IF the negative number has a greater absolute value

ZERO… IF both numbers have the same absolute value

Think of a game between two teams- The POSITIVE TEAM and The NEGATIVE TEAM.

30 + -16 … ask yourself the all important question…
“WHO WINS?
in this case the positive and then ask
“BY HOW MUCH?”
take the difference 14

14 + - 52…
“WHO WINS?”
the negative… “BY HOW MUCH?”
38
so the answer is -38


(-2 + 3) + - 6 you can work this 2 ways

(-2 + 3) + - 6 = 1 + -6 = -5 or
using all the properties that work for whole numbers
Commutative and Associative properties of addition
can change expression to (-2 + -6) + 3 or -8 + 3 = -5 you still arrive at the same solution.

You want to use these properties when you are adding more than 2 integers.
First look for zero pairs—you can cross them out right away!!
3 + (-3) = 0
-9 + 9 = 0

Then you can use C(+) to move the integers around to make it easier to add them together rather than adding them in the original order. In addition, you can use A(+) to group your positive and negative numbers in ways that make it easier to add as well.

One surefire way is to add all the positives up… and then add all the negatives up.
At this point ask yourself that all important question… WHO WINS? …
use the winner’s sign..
and then ask yourself..
BY HOW MUCH?

example:

-4 + 27 +(-6) + 5 + (-4) + (6) + (-27) + 13

Taking a good scan of the numbers, do you see any zero pairs?
YES—so cross them out and you are left with
-4 + 5 + (-4) + 13
add your positives 5 + 13 = 18
add your negatives and use their sign – 4 + -4 = -8

Okay, Who wins? the positive
By how much? 10
so
-4 + 27 +(-6) + 5 + (-4) + (6) + (-27) + 13 = 10

Pre Algebra (Period 2 & 4)

Adding/ Subtracting Fractions (Negative) 5-3


1) Double check any subtractions just as you would for integer problems


2) As yourself "Who Wins?" Place the "winners sign" in the answer box you've created

3) Stack them...Place the winner on the top (no matter the sign)
 Take the difference

3) Restate to common denominators if needed


4) Borrow if the fraction above is smaller than the fraction below

5) Make sure your answers have consistent signs - In other words, if you have a negative fraction, make sure your whole number part is also negative





EXAMPLE :


5 2/3 - 10 1/4



METHOD 1: KEEP THEM AS MIXED NUMBERS:


First of all, you know the final answer will be NEGATIVE so make sure it is!

Put bigger absolute value on top:
 and take the difference
10 1/4
-
5 2/3


Find a common denominator:


10 3/12
-5 8/12


Borrow because the top fraction portion is smaller than the bottom
9 15/12
5 8/12

Use integer rules to add or subtract:
 - 4 7/12


Check

Algebra (Period 1)

LINEAR EQUATIONS: 7-3

What do they look like (what is not a linear equation?)


The variable is to the 1 power -> like x, or y, or a, or b


What is not a linear equation? the variable is not to the 1 power - like x², x³, etc, or 1/x (x-1)



Two ways to graph:


1) 3 points using a table (like Ch 7-2)


EXAMPLE: 2x - 3y = -6


x ❘ y


0 2


3 4


-3 0

So the 3 points of (0,2) (3,4) and (-3,0)



2) 2 points using the y and x intercepts (where the line intersects the y and x axis)


Standard form of a linear equation:

Ax + By = C
 where A, B and C should not be fractions


A should be positive (y will be positive or negative)


We won't be using this form to look at the slope of the line!


This is a good format for finding the x and y intercepts!



If it's in standard form, this way works great if both the x and y coefficients are factors of the constant on the other side of the equal sign.



EXAMPLE: 2x - 3y = -6


If x = 0, y = 2


If y = 0, x = -3



Special linear equations:


Ones that are parallel to either the x or the y axis:


Lines parallel to the y axis are vertical lines:


They end up as the form x = constant with no y variable in the equation at all!


EXAMPLE: x = 4 ends up as a vertical line at x = 4


Still don't get this???


Pick of few points with the x value of 4:
(4, 0) (4, 2) (4, -3)


Graph those and join them in a line.
 What do you get???


A vertical line!




Lines parallel to the x axis are horizontal lines:


They end up as the form y = constant with no x variable in the equation at all!


EXAMPLE: y = 4 ends up as a horizontal line at y = 4


Still don't get this???


Pick of few points with the y value of 4:
(0, 4) (2, 4) (-3, 4)


Graph those and join them in a line.
What do you get???


A horizontal line!

Pre Algebra (Period 2 & 4)

Multiplying & Dividing Fractions 5-4

(skipped 5-3 negative fractions until tomorrow)


EASIEST FRACTION SKILL BECAUSE YOU DON'T NEED A COMMON DENOMINATOR!!!!



MULTIPLICATION

1. Turn any mixed number into an IMPROPER FRACTION

2. Simplify or Cross cancel if possible (it makes the math easier!)

3. Multiply numerator x numerator and denominator x denominator

4. Simplify if necessary



DIVISION:

WE NEVER DIVIDE, WE FLIP THE SECOND FRACTION AND MULTIPLY!


(never, ever touch the first fraction!)


1. Turn any mixed number into an IMPROPER FRACTION

2. FLIP THE SECOND FRACTION AND CHANGE TO MULTIPLICATION


3. Cross cancel if possible (it makes the math easier!)

4. Multiply numerator x numerator
and the denominator x denominator


5. Simplify if necessary



NEGATIVES:

Follow your integer rules (FINGER RULES) to determine the sign



VARIABLES:
You can cross cancel them as well!

Algebra (Period 1)

GRAPHING LINEAR EQUATIONS: 7-2

How do you determine whether a given number is a solution?

Plug it in, plug it in, plug it in!



How do you find a solution to an equation yourself?


Plug in for x and find y!


You can use ANY number for x


Then plug in your number and find y



How can you graph a linear equation?


Make an x/y table of values and then graph the coordinates.


You only need 3 coordinates to make a good line!


(The 3rd coordinate serves as a "check" for the other two...in case you made a mistake!)


I always try x = zero and y = zero first because it's usually easy.

Then pick another easy x value!


If this doesn't work well (you get a fraction as an answer and that's not easy to graph),
then try setting x equal to 1, then 2, then 3

Math 6 Honors (Period 6 and 7)

Negative Numbers 11-1

On a horizontal number line we use negative numbers for the coordinates of points to the left of zero. We denote the number called ‘negative four’ by the symbol -4. The symbol -4 is normally read ‘ negative 4’ but we can also say ‘ the opposite of 4.’

The graphs of 4 and -4 are the same distance from 0—>but in opposite directions. Thus they are opposites. -4 is the opposite of 4.

The opposite of 0 is 0

Absolute Value is a distance concept. Absolute value is the distance of a number from 0 on a number line. The absolute value of a number can NEVER be negative!!

Counting (also known as Natural) numbers: 1, 2, 3, 4, ….
Whole numbers 0, 1, 2, 3, 4….
Integers are natural numbers and their opposites AND zero
…-4, -3, -2, -1, 0, 1, 2, 3, 4….

The opposite of 0 is 0.

The integer 0 is neither positive nor negative.

The farther we go to the right on a number line--- the bigger the number. We can compare two integers by looking at their position on a number line.

if x < 0 what do we know? x is negative number if x > 0, what do we know? x is a positive number

We have been practicing representing integers by their graphs, that is, by points on a number line.

Make sure that your number line includes arrows at both ends and a line indicating where zero falls on your number line.
The graph of a number MUST have a closed dot right on the number line at that specific number.
Please see our textbook page 366 for an accurate example.

Algebra (Period 1)

GRAPHING ORDERED PAIRS:
7-1

Review of x y Coordinate Plane Graphing from Pre-Algebra

Cartesian plane: Named after French mathematician Descartes.


plane: a two dimensional (across and up/down) flat surface that extends infinitely in all directions.


quadrant: 2 perpendicular lines called axes split the plane into 4 regions....

quad means 4


quadrant

names: begin in the top right (where you normally write your name!) and go counterclockwise in a big "C" (remember it for "C"oordinate)


They are named I, II, III, IV in Roman Numerals



coordinate - A coordinate is the position of a point in the Cartesian plane


coordinate = "co" means goes along with (COefficient, COworker, CO-president, CO-champions)



"ordinate" means in order


So coordinate means numbers that go along with each other in a certain order


The numbers are the x and y values and the order is that the x always comes first



Also called an ordered pair (x y "ordered" and they are a "pair" of numbers)


Ordered pairs are recognized by the use of ( x , y ) format



origin = (0, 0) the center of the graph (its beginning or origin)


When you count the coordinate' s position, you count from the origin.



x comes before y in the alphabet so the order is (x, y) 
always go right or left first, then up or down



the x axis is the horizontal axis (goes across)


Remember that because the number line also is horizontal and you learn that first


(the pattern to remember is x is always first and the number line is before going up and down)



NOW LET'S GET TO WHAT YOU ACTUALLY DO!!!


1) Count your x value:


positive x, count right from origin (positive numbers are to the right of zero on number line)


negative x, count left from origin


2) Count your y value:


positive y value, count up from where your x value was (up is the positive direction)


negative y value, count down from where your x value was (down is the negative direction)



EXAMPLE:
(3, 5) Count 3 to the right from the origin, then 5 up


(3, -5) Still count 2 to the right, but now count 5 down


(-3, 5) Count 3 to the left from the origin, then count 5 up


(-3, -5) Again count 3 to the left, but now count 5 down



BUT WHAT HAPPENS WHEN
 ONE OF THE VALUES IS ZERO?


If the y value is zero it means that you move right or left, but don't go up or down:


SO YOUR POINT WILL BE ON THE x AXIS........

x axis is where y = 0 
Example: (3, 0) is a point on the x axis, 3 places to the RIGHT


Example: (-3, 0) is a point on the x axis, 3 places to the LEFT



If the x value is zero it means that you don't move right or left, you just go up or down.


SO YOUR POINT WILL BE ON THE y AXIS...........

y axis is where x = 0 


Example: (0, 3) is a point on the y axis, 3 places UP


Example: (0, -3) is a point on the y axis, 3 places DOWN

Pre Algebra (Period 2 & 4)

Adding & Subtracting Fractions 5-3

(positive only)

1) Check for a common denominator

2) If you don't have one, use the LCM as the LCD (least common denominator)

3) Use equivalent fractions to restate to the common denominator

4) When subtracting, be sure to BORROW IF YOU NEED TO!



Adding or subtracting VARIABLES:

If the variable is just in the numerator,
just follow the normal method of finding a common denominator

EXAMPLE:
x/2 + 3x/5 
The common denominator is 10

(5)x/10 + 3x(2)/10      
  (
5x + 6x)/ 
10    = 11x/10  




If the variable is in the denominator, but they are the same variables, just add/subtract normally because you have a common denominator

EXAMPLE:
3/y + 7/y = 10
/y  

If in the denominator, but the denominators are not the same, multiply the two denominators together and use equivalent fractions just as you would do with number denominators.


This time you will have to multiply by a variable.

EXAMPLE:
3/y - 7/10 
 
The LCD is 10y:

[(10)3 - (y) 7 ]/
(10) y   =

(30 - 7y)/10y

 
There's also a trick to this that I showed you in class!
You simply multiply the 2nd denominator by the 1st numerator.
Then multiply the 1st denominator by the 2nd numerator.
The denominator is the product of both denominators.
Only works if there are just 2 terms!!!

NEGATIVE FRACTIONS


1) Double check any subtractions just as you would for integer problems

2) Place the bigger fraction on the top (no matter the sign)

3) Restate to common denominators if needed

4) Borrow if the fraction below is larger than the fraction above

5) Make sure your answers have consistent signs - In other words, if you have a negative fraction, make sure your whole number part is also negative

OR

1) You can simply make all mixed numbers into improper fractions first

2) Find a common denominator

3) Use integer rules with the numerators

4) Restate back into mixed numbers if required

EXAMPLE using both methods:


5 2/3 - 10 1/4


KEEP THEM AS MIXED NUMBERS:
First of all, you know the final answer will be NEGATIVE so make sure it is!
STACK THEM!! With the WINNER on TOP

10 1/4
5 2/3


Find a common denominator:

10 3/12

5 8/12


Borrow because the bottom number is bigger than the top number

9 15/12

5 8/12

Use integer rules to add or subtract:

-4 7/12


Check: If so, you've got the answer:
(if not, you needed to borrow and you forgot to!)
-4 7/12



Pre Algebra (Period 2 & 4)

Change Repeating Decimals to Fractions

Step 1: set up "n = the repeating decimal
Step 2: determine how many numbers are under the bar
Step 3: use that number as a power of 10
Step 4: multiply both sides of the equation in Step 1 by that power of 10
Step 5: Rewrite the equations so that you subtract the 1st equation FROM the 2nd equation
Step 6: Solve as a 1 or 2-step equation
Step 7: simplify, if necessary

REMEMBER-- SOMETIMES YOU NEED TO GET THE DECIMAL OUT OF THE NUMERATOR--> MULTIPLY BOTH THE NUMERATOR AND THE DENOMINATOR BY A POWER OF 10


example:
change .416666... into a fraction
let n = .416666...
notice there is one 1 number that is repeating so it is only 10 to the 1st power
multiply both sides by 10
10n = 4.16666....
now subtract the 1st equation

10n = 4.16666...
-n = 0.41666...
9n = 3.75

divide both sides by 9
9n = 3.75
9 9

or 9n/9 = 3.75/9

move the decimal 2 places in both the numerator and denominator
n = 375/900
simplify
n = 5/12

LEARN THE MOST COMMON ONES BY HEARS
Need to know:
1/9 family
1/11 family
Easy trick to recall
If the repeating decimal starts repeating right after the decimal, you can easily get the fraction just by putting the same number of 9's as the length of the repeating decimal.. then simplify:
Examples:
.4444... = 4/9
.454545.... = 45/99 = 5/11
.162162162... = 162/999 = 18/111

Pre Algebra (Period 2 & 4)

Fractions & Decimals 5-2 (cont'd)

Ordering or comparing fractions:(last method)

4: Make them into decimals because DECIMALS = FRACTION posers!

(or decimals are just fraction wannabes!)
Today, we will change fractions to decimals and decimals to fractions.

How to change a fraction to a decimal
1.
Divide (ALWAYS WORKS!)

EXAMPLE: 3/4 = 3 divided by 4 = .75

If the quotient starts repeating, then put a bar over the number(s) that repeat. OR

2. Use equivalent fractions (SOMETIMES WORKS!)

Works if the denominator can be easily made into a power of 10

SAME EXAMPLE: but this time you will multiply by 25/25 to get 75/100 = .75



3. MEMORY! Some equivalencies you should just know!
EXAMPLE: 1/2 = .5


IF IT'S A MIXED NUMBER, JUST ADD THE WHOLE NUMBER AT THE END!

EXAMPLE: 8 3/4

For the fraction: 3 divided by 4 = .75

Add the whole number: 
8.75


IF THE MIXED NUMBER OR FRACTION IS NEGATIVE, SO IS THE DECIMAL!


CHANGING TERMINATING DECIMALS TO FRACTIONS:
EASY!!!
Read it, Write it, Simplify!



EXAMPLE:

Change .24 to a fraction

1) READ IT: 24 hundredths

2) WRITE IT: 24/100

3) SIMPLIFY: 24/100 = 6/25



EXAMPLE with whole number:

Change 7.24 to a fraction

The 7 is the whole number in the mixed number so you just put the 7 at the end

1) READ IT: 24 hundredths

2) WRITE IT: 24/100

3) SIMPLIFY: 24/100 = 6/25

4) 7 6/25



HOW TO CHANGE REPEATING DECIMALS TO FRACTIONS-
FIrst know some by heart.. easier..
1/3 = .333333 = .3 with a vinculum over the 3... that's a bar.

1/9 family

Notice that you use the number found in the numerator, add a decimal point in front of it and add a bar above it.

1/11 family is a little different. You multiply the numerator by 9 ( making sure 1/11 has a two digit number after the decimal... and put a bar over the two digits.

To get exact answer when doing math operations with repeating decimals--> you must make decimals into their fraction equivalents and do operations with fractions

1/7 family really special!!!

Take a look and see if you remember the pattern we talked about in class today!!

To change repeating decimals to fractions follow these steps:
1) let n = the repeating decimal
2) multiply both sides by a power of 10 equal to the number of places under the vinculum (the bar)
3) rewrite n = the repeating decimal under #2
4) subtract n on the left side and the repeating decimal on the right
5) solve as a 1-step equation
6) multiply the numerator and the denominator by a power of 10 if necessary to get the decmial out of the numerator
7) simplify

We used

= 4.66666....

let n = .4166666...
multiply by a power of 10 in this case by 10¹ or just 10
10n =4.166666....
-1n = 0.416666....
9n = 3.75

then divide both sides by 9

9n/9 = 3.75/9

n = 3.75/9

need to multiply the numerator and the denominator by 100
375/900

simplifies to 5/12

Algebra (Period 1)

Using Equations That Factor 6-9 Cont'd

Word Problems continued...
We looked at a number of word problems... translated them to an equation and solved. The following should be in your spiral notebook:

1. The product of two consecutive positive even integers is 48. Find the two integers.

Let x = the first positive even integer
let x + 1 represent the second positive even integer

x(x +1) =48
x² + x = 48
move the 48 to the left side, setting the equation to zero

x² + x - 48 = 0
NOW factor
(x + 8)(x - 6) = 0
x = -8 x = 6
Stop and re-read the equation... It says positive even integers so the only solution is
x = 6
BUT... you need to find the two integers
x = 6
and x + 2 = 8
{6,8}

2. One side of a rectangle is 4 inches longer than the other. If the sides are each increased by 2 inches, the area of the new rectangle is 60 inches squared. How long are the sides of the original rectangle?

Let w = the width of the rectangle.
let w + 4 = the length of the rectangle. ( re-read the equation to get this information!!)
Then it says "sides are each increased by 2 inches"
so we have w + 2
and (w+4) + 2, which is just w + 6
Now the area is 60 inches squared so we know A = lw
(w +2)(w + 6) = 60
FOIL or use the box method...
w² + 8w + 12 = 60
We need to use the ZERO Products Property so we need to move the 60 to the left, setting the equation equal to ZERO
w² + 8w + 12 - 60 = 0
w² + 8w - 48 = 0
FACTOR
(w + 12)(w -4) = 0
w = -12 and w = 4
BUT A rectangle can't have a negative length so -12 is NOT a solution.

If w = 4
w + 4 = 8
The original rectangle's sides are 4 inches and 8 inches.

3. The sum of the squares of two consecutive even integers is 244. Find the two integers.
let n = the first even integer
let n + 2 = the second even integer

The sum of the squares---> n² + (n +2)² = 244
n² + n² + 4n + 4 = 244
combine like terms and move 244 to the left side of the equation you get
2n² + 4n - 240 = 0
Factor out the GCF
2(n² + 2n - 120) = 0
factor
2(n + 12)(n - 10) = 0
n = -12 and n = 10
This time both of those fit the requirements. Both are solutions BUT you need two sets of pairs.
n + 2 when n = -12 is - 12 + 2 = -10
and
n + 2 when n = 10 is 10 + 2 = 12

{-12, -10} and (10, 12)

4. The sum of twice a number and the number squared is -1. What is this number?
let x = a number
2x + x² = -1
2x + x² + 1 = 0
BUT WAIT... you can't work with this trinomial in this order... put in descending order and THEN factor..
x² + 2x + 1 = 0
Wait... do you see?... It's a Trinomial squared!!
(x + 1)² = 0
x = -1

5. Five times a number decreased by 6 is equal to the number squared. What is the number?

Let x = the number
5x - 6 = x ²
Keep the x² positive... that is move the other terms to it's side... easier to factor that way..
you get
0 = x² - 5x + 6
or
x² - 5x + 6 = 0
factor...
(x -3)(x -2) = 0
x = 3 and x = 2

We did a few more from our textbook on Page 294

Algebra (Period 1)

Using Equations That Factor 6-9


WORD PROBLEMS WITH FACTORING

DRAW A PICTURE IF NECESSARY TO HELP YOU UNDERSTAND THE PROBLEM!
You are supposed to know basic Geometry Formulas!!!


1) Translate the words into an equation

2) If necessary, move all terms to the left side leaving only zero on the right side of the equation

3) Factor the left side

4) Set each factor equal to zero and solve.


5) If the problem calls for real life things like area or time, eliminate the NEGATIVE answer because certain real life things can never be negative!

The product of one more than a number and one less than the number is 8

Write a let statement
x = the number
so
(x +1)(x -1) = 8

you must multiple the two terms
x² -1 = 8
now using the zero products property have all terms on the left
x² - 9 = 0
WOW-- its the difference of two squares...
(x+3)(x-3) = 0
set each to zero
x+ 3 = 0 and x- 3 = 0
or
x = -3 and x = 3
{-3, 3}

The square of a number minus twice the number is 48. Find the number...
Let n = the number

n² - 2n = 48
n² - 2n -48 = 0 Now factor
(n -8)(n+ 6) = 0
n = 8 and n = -6
{-6, 8}


The product of two consecutive integers is 156, Find the integers...
Let x represent the 1st integer then
x + 1 is the 2nd integer

x(x +1) = 156
x² + x = 156

x² + x- 156 = 0
(x + 13)(x -12) = 0
x = -13 and x = 12

But wait you have found only one of the integers..
if x = -13 x + 1 = -13 + 1 = -12

and if x = 12 then x + 1 = 13 so you have two pairs of answers
{-13,-12,} and {12, 13}

The length of a rectangle is 5 cm greater than the width. The area is 84 cm²
Find the length and the width...
Okay, we know A = lw

Re reading the information we decide to
let w = the width
and then w +5 = the length
(w + 5)w = 84
or w (w + 5) = 84
w² + 5w = 84
w² + 5w - 84 = 0
(w + 12)(w -7) =84
so
w = -12 or w = 7
BUT a width can't be negative so we don't need to use -12
if the width is 7,
then w + 5 or 7 + 5= 12 must be the length
SOLUTION: width is 7 cm and the length is 12 cm

Math 6 Honors (Period 6 and 7)

Greatest Common Factor 5-5

If we list the factors of 30 and 42, we notice
Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42

We notice that 1, 2, 3, and 6 are all COMMON factors of these two numbers. The number 6 is the greatest of these and therefore is called the
GREATEST COMMON FACTOR of the two numbers. We write
GCF(30,42) = 6

Although listing the factors of two numbers and then comparing their common factors is one way to determine the greatest common factor, using prime factorization is another easy way to find the GCF

Find GCF(54, 72)
54 = 2 ⋅ 3 ⋅ 3 ⋅ 3
72 = 2 ⋅ 2 ⋅ 2 ⋅ 3 ⋅ 3
Find the greatest power of 2 that occurs IN BOTH prime factorization. The greatest power of 2 that occurs in both is just 2 ¹
Find the greatest power of 3 that occurs IN BOTH prime factorizations. The greatest power of 3 that occurs in both is 3²
Therefore
GCF(54, 72) = 2 ⋅ 3² = 18

In class we circled the common factors and realized that
GCF(54, 72) = 2 ⋅ 3 ⋅ 3 = 18


Fin the GCF( 45, 60)
45 = 3 ⋅ 3⋅ 5
60 = 2⋅ 2⋅ 3⋅ 5
Since 2 is NOT a factor of 45-- there is NO greatest power of 2 that occurs in both prime factorizations.
The greatest power of 3 is just 3¹
and the greatest power of 5 is just 5¹
Therefore,
GCF(45,60) = 3⋅ 5 = 15

The number 1 is a common factor of any two whole numbers!! If 1 is the GCF , then the two numbers are said to be RELATIVELY PRIME. Two numbers can be relatively prime even if one or both of them are composite.

Show that 15 and 16 are relatively prime
List the factors of each number
FACTORS of 15: 1, 3, 5, 15
FACTORS of 16: 1, 2, 4, 8, 16

Since the GCF(15,16) = 1. The two numbers are relatively prime!!

Math 6 Honors (Period 6 and 7)

Prime Numbers & Composite Numbers 5-4

A prime number is one that has only two factors: 1 and the number itself, such as 2, 3, 5, 7, 11, 13...
A counting number that has more than two factors is called a composite number, such as 4, 6, 8, 9, 10...

Since one has exactly ONE factor, it is NEITHER PRIME NOR COMPOSITE!!
Zero is also NEITHER PRIME NOR COMPOSITE!!

Every counting number greater than 1 has at least one prime factor -- which may be the number itself.
You can factor a number into PRIME FACTORS by using a factor tree or the inverted division, as shown in class.

Using the inverted division, you also start with the smallest prime number that is a factor... and work down
give the prime factors of 42
2⎣42
3⎣21
7

When we write 42 as 2⋅3⋅7 this product of prime factors is called the prime factorization of 42.

Two is the only even prime number because all the other even numbers have two as a factor.

Explain how you know that each of the following numbers must be composite...
111; 111,111; 111,111,111; and so on....
Using your divisibility rules you notice that the sums of the digits are multiples of 3.

List all the possible digits that can be the last digit of a prime number that is greater than 10.
1, 3, 7, 9.

Choose any six digit number such that the last three digits are a repeat of the first three digits. For example
652,652. You will find that 7, 11, and 13 are all factors of that number... no matter what number you choose... why is that???? email me your response.