Understanding Prime and Composite Numbers

The video tutorial explains the difference between prime and composite numbers, providing definitions and examples. It demonstrates how to determine if a number is prime or composite by finding its factors. The tutorial covers specific examples, including numbers 15, 17, 37, 81, and 127, and explains the process of verifying a number's primality through division by prime numbers.

What is a prime number?

• A number that is even

• A number that is odd

• A number with more than two factors

• A number divisible by 1 and itself only

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CCSS.4.OA.B.4

Which of the following is a composite number?

• 2

• 3

• 5

• 15

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CCSS.4.OA.B.4

Why is 17 considered a prime number?

• It is a multiple of 3

• It has only two factors: 1 and 17

• It is divisible by 2

• It is an even number

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CCSS.4.OA.B.4

What makes 37 a prime number?

• It is an even number

• It has only two factors: 1 and 37

• It is divisible by 5

• It is a multiple of 6

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CCSS.4.OA.B.4

Which of the following is a factor of 81?

• 7

• 9

• 11

• 13

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CCSS.4.OA.B.4

Why is 81 considered a composite number?

• It is divisible by 3

• It is a prime number

• It has only two factors

• It is an odd number

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CCSS.4.OA.B.4

What is the first step in determining if 127 is prime?

• Divide by 3

• Check if it is even

• Divide by 2

• Check if it is a multiple of 5

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CCSS.4.OA.B.4

Why is 127 considered a prime number?

• It is divisible by 7

• It is an even number

• It has no prime factors other than 1 and itself

• It is a multiple of 11

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CCSS.4.OA.B.4

What is the significance of the remainder in the division process for prime checking?

• A remainder of two indicates a factor

• A remainder of one indicates a factor

• A remainder of zero indicates a factor

• A remainder of three indicates a factor

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CCSS.4.OA.B.4

Which number is used as the last prime to check divisibility for 127?

• 13

• 11

• 7

• 17

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CCSS.4.OA.B.4