Friday, September 10, 2010

I have attached class notes from class yesterday and today!  

There is homework but it’s worksheets, so if you were not in school today just review the notes and make sure you understand how to find the LCM and GCF.

If you were here, complete both worksheets for class on Monday.

6th grade notes 

September 8, 2010

The math review test will be on Wednesday, September 22, 2010.

Greatest Common Factors

Factors are numbers that are used to multiply to get a product.
The factors of 12:
12: 1, 2, 3, 4, 6, 12

The greatest common factor is the largest factor shared by two or more numbers. There are many ways to find this number. Two strategies are listed below.

Find the GCF of 12 and 8

Strategy #1
List the factors of both numbers and look for the largest shared factor.

8: 1, 2, 4, 8
12: 1, 2, 3, 4, 6, 12

The numbers 8 and 12 have three common factors. The largest one, the greatest common factor is 4.

Strategy #2

Make factor trees and list the prime factors.

12 = 2 x 2 x 3 8 = 2 x 2 x 2

Multiply all the prime factors the numbers have in common.

2 x 2 = 4

The greatest common factor is 4.

As a general rule it is usually easier to do the smaller numbers in your head. 

The smaller numbers you are unsure of would be easier to find using strategy #1. For larger numbers it is probably easier and more efficient to use strategy #2.

September 10, 2010

Class notes

Lowest Common Multiple

Multiples are the numbers that are the product of a number and another factor.

The multiples of 5.

5: 5, 10, 15, 20, 25, 30, 35, ….

The lowest common multiple is the smallest multiple shared by two or more numbers. There see many ways to find this number. Two strategies are listed below. 

Find the LCM of 6 and 8

Strategy #1

List the multiples of the two numbers and compare the multiples to find the lowest.

6: 6, 12, 18, 24, 30, 36, 42

8: 8, 16, 24, 32, 40

Strategy #2

Make a factor tree for each number. Multiply the most prime factors for the combined numbers.

The prime factors 
6: 2 x 3

8: 2 x 2 x 2

The LCM = 2 x 2 x 2 x 3

The LCM = 24