## Friday, February 26, 2010

### Subtracting Fractions with like Denominators.

*When we say like denominators it means the same bottom numbers.*

Subtracting Fractions with like denominators basically has the same rule as Adding Fractions with like Denominators.

When adding or subtracting fractions with like denominators you start by adding or subtracting the numerator, and the denominator stays the same.

Examples for adding Fractions with like denominators:

1/4 +1/4=2/4

Examples for Subtracting Fractions with Like Denominators:

3/4-2/4= 1/4

Simplifying your answer:

When simplifying your answer you first find the greatest common factor of the numerator and denominator, then divide the numerator and denominator by the greatest common factor. If you can not find a factor for the numerator and denominator then it has already been simplified to it's lowest form.

eg.

7/10-3/10= 4/10= 2/5

1/4+1/4= 2/4= 1/2

Click here for a link to a helpful site on adding and subtracting fractions with common denominators.

Now please enjoy the video.

## Monday, February 8, 2010

### Divisibility

Divisibility Rules - Quick ways to determine if a number is divisible by another number.

Rule for

*2*- All even numbers are divisible by 2.

- Any number ending in 0,2,4,6,8

eg.

- 4 is divisible by 2

- 280 is divisible by 2

- 2971 is

*divisible by 2*

**not**Rule for

*5*- Any number that ends in 5 or 0.

eg.

- 155 divisible by 5

- 8974 is

**divisible by 5**

*not*Rule for

*10*- Any number that ends in 0.

eg.

- 1070 is divisible by 10

- 27367 is not divisible by 10

- 360.4 is not divisible by 10

- 364.0 is not divisible by 10

Quotient - Is the result of a division question.

eg.

- 12 divided by 2 = 6. Quotient is 6

Rule for

*4*

*- Look at the last 2 digits, are they divisible by 2 twice?*

eg.

**The rule for 4** - If the last 2 digits are divisible by 2 twice, then the number is divisible by 4.

Rule for *8* - If the last 2 digits are divisible by 2 three times, then the number is divisible by 8.

eg.

16 divided by 2 = 8 8 divided by 2 = 4 4 divided by 2 = 2 = yes

18 divided by 2 = 9 9 divided by 2 = 4.5 = no

17948 = 48 divided by 2 = 24 24 divided by 2 = 12 12 divided by 2 = 6 = yes

Rule for* 7* - Use calculator. There is no short-cut yet! You should find one and name it after yourself.

Rule for 3 - Add up all the digits until you have a single digit remaining. If that digit is divisible by 3 the number is divisible by 3.

eg.

93 = 9+3 =12 1+2=3 = yes

273 = 2+7+3=12 1+2+3 = yes

1045 = 1+0+4+5=10 1+0=1 = no

Rule for *6* - Any number that is divisible by 2 and 3.

Rule for *9* - Add up all the digits until you have 1 digit. If that digit is 9 the number is divisible by 9.

eg.

18 = 1+8=9 = yes

54 = 5+4=9 = yes

468 = 4+6+8=18 1+8=9 = yes

2345 = 2+3+4+5=14 1+4=5 = no

Rule for *0* - Nothing is divisible by 0.

*If you guys still have problems with Divisibility click on this website* =

http://math.about.com/library/bldivide.htm

Enjoy the video :D

## Friday, February 5, 2010

### Homework Package

Textbook pages:

2) pages 168-170 all

3) pages 190-193

4) pages 180-182 #1-11

5) pages 162-164 all

6) pages 174-176 #1-15

Questions:

7) Trudy, Shana, Kendra, Tracie, and Saira are on Team A and Jordan, Micheal, Terrance, Sean, and Suni are on Team B. Use a tree diagram to show all the possible outcomes if the coach on Team B assigns every player on Team B to defend a player on Team A. Also write the sample space.

8) A toonie is flipped and a four sided die is rolled.Using a chart find P( tails and an odd # )

9) Create and answer probability questions with the results ( answers ) of 0%, 20%, 60%, and 100%.

10) A jar contains 4 pink marbles , 26 purple marbles, and 9 orange marbles. If the marbles are drawn out at random what are the chances you would get two pink marbles without replacing the first marble.

11) All the corrections for the probability unit test.

**DUE ON MONDAY!!!!!!!!**

Here is a link that might help you with your homework package:

http://www.mathgoodies.com/lessons/vol6/intro_probability.html