Prime Numbers

Slide 1: Prime numbers Composite numbers Neither prime nor composite How to know?

Slide 2: Prime and composite numbers are all about multiplication Multiplication math vocabulary: The two numbers being multiplied factors. together are each called The answer in a multiplication problem is product. called the

Slide 3: Multiplication factor x factor = product

Slide 4: Prime Numbers To determine if a number is a prime number, place it in the product position. = X Factor Factor Product Is this number a prime number?

Slide 5: Prime Numbers • Must have ONLY two possible, unique factors. (Both factors cannot be the same.) • One factor must be 1. • One factor must be a whole number, but not 0 or 1. X = Factor Factor Product same number same number as 1 as the product, one of the factors, but not 0 or 1. but not 0 and not 1

Slide 6: Whole numbers In case you forgot: Whole numbers are the the number 0, and the natural numbers which start at positive one— {0, 1, 2, 3...}

Slide 7: Prime Numbers X = 3 1 3 same number same number as as the product, one of the factors, but not 0 or 1. but not 0 and not 1 3 is a prime number. 2. There are ONLY two possible, unique factors. (No other two numbers multiplied together have a product of 3 and both factors are different numbers.) 2. One factor is 1. 3. One factor is a whole number, but not 0 or 1.

Slide 8: Prime Numbers misconception is A common that odd numbers are always prime numbers but, that’s not true.

Slide 9: Prime Numbers Some odd numbers, like 9 have more than two factors. 9 x 1 = 9, 3 x 3. but so does Consequently, 9 is not a prime number.

Slide 10: Prime Numbers 51 is tricky! It is an odd number. It looks like only 51 x 1 = 51, but 17 x 3 = 51 too. 51 is not a prime number. HINT: Divisibility rules and multiplication tables can help you discover that a number that seems like a prime number really isn’t.

Slide 11: Prime Numbers However, even numbers are never prime numbers with one exception— the number 2.

Slide 12: Prime Numbers 2 is a prime number, because the only two factors of 2 are 2 x 1 = 2. Every other even number has 2 as a factor too (that’s why no other even number is a prime number).

Slide 13: Composite Numbers Numbers with more than two factors are called composite numbers. Numbers that aren’t prime numbers are composite numbers.

Slide 14: The special case of the number 1 The number 1 is not a prime number and, it is not a composite number. Why? because, the number 1 only has one factor, not two different factors. 1x1=1

Slide 15: The special case of the number 0. Zero is another special number. Zero can not be a prime number because, every number is a factor of 0. 0 x 1 does equal 0, but 0 x anything at all = 0 Zero is not a composite number either.

Slide 16: Only 0 and 1 are neither prime nor composite numbers. All other whole numbers are either prime or composite numbers.

Slide 17: Congratulations! That’s how to tell a prime number from a composite number. Remember, if in doubt; with big numbers, use divisibility rules. With smaller products, use multiplication tables. And all even numbers, except 2, are always composite.

Slide 18: Notes for teachers on texts correlation: Correlates with Glencoe Mathematics (Florida Edition) texts: Mathematics: Applications and Concepts Course 1: (red book) Chapter 1 Lesson 3: Prime Factors Mathematics: Applications and Concepts Course 2: (blue book) Chapter 5 Lesson 1: Prime Factorization Pre-Algebra: (green book) Chapter 4 Lesson 3: Prime Factorization For more information on my math class see http:// walsh.edublogs.org

Slide 19: Notes for teachers on design This slide presentation was created using Microsoft Office PowerPoint 2003 part of Microsoft Office Standard Version for Students and Teachers. Finally, thank you. I hope this is of help to your students. Taleese