 PRIME AND COMPOSITE NUMBERS

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PRIME AND COMPOSITE NUMBERS
LESSON 3

PRIME NUMBERS A Prime Number can be divided evenly only by 1, or itself. EXAMPLES: 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47

COMPOSITE NUMBERS A Composite Number can be divided evenly by numbers other than 1 or itself. EXAMPLES: 4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,26,27,28,30,32,33,34,35,36,38,39,40

FACTORS A number may be made by multiplying two or more other numbers together. The numbers that are multiplied together are called factors. EXAMPLE:

FACTORS A number may be made by multiplying two or more other numbers together. The numbers that are multiplied together are called factors. EXAMPLE: 3 X 4 = 12 PRODUCT FACTOR FACTOR

FACTORS Therefore PRIME numbers have 2 factors: one and itself.
COMPOSITE numbers have more than two factors. The number ONE only has one factor (1), therefore it is not prime nor composite but SPECIAL.

GCF GCF – GREATEST COMMON FACTOR
The GCF is the highest factor that two or more numbers have in common. EXAMPLE: The factors of 18 are {1,2,3,6,9,18} The factors of 24 are {1,2,3,4,6,8,12,24}

GCF GCF – GREATEST COMMON FACTOR
The GCF is the highest factor that two or more numbers have in common. EXAMPLE: The factors of 18 are {1,2,3,6,9,18} The factors of 24 are {1,2,3,4,6,8,12,24} The GCF is 6.

PRIME FACTORS Factors that are prime numbers.
When a composite number is written as a product of all of its prime factors, we have the prime factorization of the number. EXAMPLE: the number 72 can be written as a product of primes as: 72 =2x2x2x3x3 . The expression "2x2x2x3x3" is said to be the prime factorization of 72.

TRY THIS ONE Find the PRIME factors of 32 SOLUTION:

TRY THIS ONE Find the PRIME factors of 32 SOLUTION: 32 4 x 8
2 x x x 2 x 2 = 25

LCM LCM – LOWEST COMMON MULTIPLE
A common multiple is a number that is a multiple of two or more numbers. The common multiples of 3 and 4 are: 0, 12, 24,….

LCM The least common multiple (LCM) of two numbers is the smallest number (not zero) that is a multiple of both. EXAMPLE: Multiples of 3: 6,9,12,15,18,21,24,… Multiples of 4: 8,12,16,20,24,…. LCM of 3 and 4 is:

The least common multiple (LCM) of two numbers is the smallest number (not zero) that is a multiple of both. EXAMPLE: Multiples of 3: 6,9,12,15,18,21,24,… Multiples of 4: 8,12,16,20,24,…. LCM of 3 and 4 is: 12