Notes 8 th Grade Pre-Algebra McDowell

LCM9/25 LCM Least common multiple The smallest number that is a multiple of both numbers

Steps To Find LCM 1. Make a multiplication table for each number 2. Compare the multiplication tables 3. Pick the smallest number that both (all) tables have

Example Find the LCM of 8 and Make a mult table 2. Compare 3. Find the smallest match The LCM of 8 and 3 is 24

You Try Find the LCM between 1.10 and and 7

Comparing And Ordering fractions Manipulate the fractions so each has the same denominator Compare/order the fractions using the numerators (the denominators are the same)

You try Workbook p 76 # all

Fractions and Decimals9/28 a decimal that ends 1¼ or 1.25 When the same group of numbers continues to repeat forever 4 or Terminating Decimal Repeating Decimal

1. Keep the whole number a whole number 2. Divide the numerator by the denominator Converting Fractions To decimals Example

Converting Terminal decimals to fractions 1. Find the place value of the terminating decimal 2. Place the numbers after the decimal over the place value Keep whole numbers as whole numbers 3. Simplify the fraction to lowest terms

Example The 5 is in the thousandths place so 1000 is the denominator Simplify 925  

3. Subtract n from both sides Remember n = = n Converting Repeating decimals to fractions 1.Let the decimal = n 2. Multiply both sides by Divide both side by 99 to solve for n 0.6 x 100 = n x = 100n n 66 = 99n

99 4. Divide both side by 99 to solve for n 66 = n Reduce the fraction 66  11= n 99  11 2 = n 3

You try Workbook p 78 # 3-21 every 3 rd

Adding and Subtracting Fractions9/29 2. Find a common denominator 3. Add or subtract the numerators Steps 4. Keep the common denominator 5. Write in simplest form (change all improper fractions back into mixed numbers) 1. Convert all mixed numbers into improper fractions

Example Common denominator so add or subtract the numerator Already in simplest form

Example Common denominator so add or subtract the numerator Already in simplest form because we do not know what x is

Example Find a common denominator Add or Subtract numerators 24 x 4 Already in simplest form

Converting A Mixed Number To an Improper MAD face 1. Multiply the denominator by the whole number then add the product to the numerator 2. That is the new numerator— keep the old denominator Multiply, Add, keep the Denominator

6 x

1. Divide the numerator by the dominator Converting An Improper To a Mixed # 2. The quotient is the whole number 3. The remainder is the new numerator 4. Keep the same denominator

Example Convert 26 to a mixed number R 2

Example 1. Convert all mixed numbers into improper fractions 2. Find a common denominator 3. Add or subtract the numerators 4. Keep the common denominator 5. Write in simplest form

Additional Examples

You try Workbook p 80 # all

Multiplying and Dividing Fractions9/30 2. Simplify by taking common factors out of the numerators and denominators 3. Multiply numerators together Steps to multiply fractions 4. Multiply denominators together 5. Write in simplest form (change all improper fractions back into mixed numbers) 1. Convert all mixed numbers into improper fractions

Example 2. Simplify by taking common factors out of the numerators and denominators 55  5 3. Multiply numerators together 4. Multiply denominators together 5. In simplest form

Example 2. Simplify by taking common factors out of the numerators and denominators 3. Multiply numerators together 4. Multiply denominators together 5. In simplest form  x  x  2  2

Additional Examples

2. Keep 1 st fraction Steps to divide fractions 3. Change Multiplication to division 1. Convert all mixed numbers into improper fractions 4. Flip Write the reciprocal of the 2 nd fraction 5. Follow steps to multiply fractions

Example Keep X Change Flip Multiply 44 44

You try Workbook p 82 # all

Chapter 5 Review10/1

Chapter 5 Quiz10/2