GCF, LCM, and Prime Numbers

Prime factorization of 20 is

• 1 x 20
• 4 x 5
• 2 x 5 x 5
• 2 x 2 x 5

What is the prime factorization of 30?

• 3x3x5
• 2x3x6
• 2x3x5
• 3x10

What is the GCF of 20 and 30?

• 5
• 2
• 10
• 20

What is the greatest factor of 28 and 49?

• 1
• 2
• 7
• 12

What is the least common multiple (LCM) of 5 and 20?

• 4
• 5
• 20
• 100

What is the least common multiple (LCM) of 4 and 10?

• 4
• 40
• 15
• 20

Use a number tree to find the prime factorization of 65

• 5x3x2x2
• 7x6x5
• 5x3x3x2
• 7x5x4

Use a factor tree to find the prime factorization of 65

• 5x3x2x2
• 7x6x5
• 5x3x3x2
• 7x5x4

Is 5 prime or composite? 

• Prime
• Composite

A prime number

• has one factor
• has more than 2 factors
• has 100 factors
• has exactly 2 factors: 1 and the number