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Fraction Unit Test Review 2013. Prime and Composite Numbers. A prime number has only 2 factors (and 2 arrays). A composite number has more than 2 factors (and more than 2 arrays). Remember, we always list our factors in a T chart!. Which number is a prime number? A. 6 B. 15 C. 39
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Prime and Composite Numbers • A prime number has only 2 factors (and 2 arrays). • A composite number has more than 2 factors (and more than 2 arrays). • Remember, we always list our factors in a T chart!
Which number is a prime number? • A. 6 • B. 15 • C. 39 • D. 11
Which number is composite? • A. 39 • B. 7 • C. 31 • D. 17
GCF – Greatest Common Factor • The GCF is the largest (or greatest) factor that two numbers have in common. Factors are two numbers you multiply together in order to find the product of a multiplication problem. • Remember: There are a couple strategies we used to find GCF; listing factors in T charts and upside down division (prime factorization).
Find the GCF of 8 and 12. • The GCF is used to DIVIDE a numerator and a denominator to find the simplest form. • A. 24 • B. 6 • C. 8 • D. 4
LCD – Least Common Denominator • The LCD is the first (least/smallest) • multiple that two numbers have in common. • Remember: multiples go on forever, you’re counting by a certain number. • Example: Multiples of 6 • 6, 12, 18, 24, 30, 36, 42, 48, 54, 60….
What is the LCD of 8 and 6? • A. 2 • B. 24 • C. 14 • D. 12
Divisibility Rules: • Divisibility Rules provide short cuts to tell if a number can be divided evenly by another number. • Divisibility Rules - • 2: if a number ends in 0, 2, 4, 6, 8 • 3: add up the digits, if the sum is a multiple of 3 then the # is divisible by 3 • 5: ends in 0 or 5 • 6: Must be divisible by 2 AND 3 • 9: add up the digits, if the sum is a • multiple of 9 then the # is divisible by 9
Which numbers divide 2, 034 evenly? • A. 3 and 9 • B. 3, 9, and 6 • C. 3 only • D. 6 only
Simplifying Fractions • Fractions must be simplified (you want your denominator to represent the largest pieces possible which means the smallest number possible). • Strategies: Find the GCF of the numerator and denominator and divide! • Check using divisibility rules! • Example: 2 = 1 • 4 2
2/5 2/8 3/5 3/6 reduce 16/24 3/7 4/9 3/8 2/3 4/5
Mixed Numbers • A mixed number contains a whole number AND a fraction. • We know how to change mixed numbers to fractions greater than one – • Strategies: * draw picture model • * use M.A.D. (Multiply, Add • move over Denominator)
Choose the fraction greater than one that is equivalent to the mixed number • 6 ¾ • A. 13/4 • B. 24/4 • C. 27/4 • D. 63/4
Fractions Greater Than One • It is NOT proper to have the larger number in the numerator and the smaller number in the denominator. This represents more than 1 whole! • Example: 45 • 7 • Strategies for changing improper fractions to mixed numbers – • * Divide (The remainder • is your new numerator.)
Choose the mixed number that is equivalent to the fraction greater than one and is written in simplest form. • 35 • 8 • A. 3 5/8 • B. 4 3/8 • C. 8 3/5 • D. 3 4/8
Adding and Subtracting Fractions • With Like Denominators • Remember: when the denominators are the same you can go ahead and add or subtract….just slide the denominator over • Example: 8 + 3 = 11 • 12 12 12 • DON’T FORGET TO SIMPLIFY IF • NECESSARY!
Be sure to simplify if needed! • Mrs. Wilson is baking brownies for her class. The recipe calls for 1/8 cup of • chocolate chips but she is going to double the recipe. What amount of chocolate chips will she need? • A. 2/8 cup • B. 2/16 cup • C. ¼ cup • D. 7/8 cup
Simplify as needed. • 4 - 2 = • 6 6 • A. 6/6 • B. 1/3 • C. 2/6 • D. 0
Adding and Subtracting Fractions • With Unlike denominators • Remember: You CAN NOT add or subtract unless your denominators are the same. • Steps: 1. Find the LCD. • 2. Create equivalent fractions. (Whatever you do • to the bottom, you’ve got to do • to the top! • 3. Add/Subtract • 4. Simplify as needed
Additional Practice • Order from greatest to least • 5.894, 5.489, 4.895, 5.984 • Frank had 3 lengths of rope. Which is the largest. • A. ¾ yard • B. ½ yard • C. 7/8 yard
Additional Practice • 3 + 3 + 2 + 1 = • 4 4 4 4 • Find the LCM of 12 and 16. • Is 56 is a prime or composite number? • What is the GCF of 49 and 21?