Prime & Composite Numbers

Prime & Composite Numbers

by Rolando Alvarez

Poll

Have you ever heard of the terms prime and composite?

• Yes, I know what they are!

• No, never!

• I've heard of them but I don't exactly know what they are .

​So what are they?

​Prime number- a number greater than 1 that that has only 1 set of factors (1 and itself).

​

​

​Composite number- number that has two or more set of factors.

​

​(One set=2 factors)

​So what does this mean?

​Prime numbers- only have one set of factors, 1 and itself. In other words, not divisible by any other number other than 1.

​

​Examples:

• ​3

• ​5

• ​7

• ​11

• ​17

In contrast...

​Composite numbers- these numbers have more that one set of factors, or are divisible by multiple numbers other than one.

​Examples:

• ​4

• ​6

• ​8

• ​14

• ​20

​Let's Review!

Multiple Choice

Composite numbers are numbers with how many sets of factors?

• Any number of factors.

• More than one set of factors.

• Only one set of factors, 1 and itself.

Multiple Choice

Prime numbers are numbers with how many sets of factors?

• Any number of factors.

• More than one seton factors.

• Only one set of factors, 1 and itself.

Poll

Is 2 a prime or composite number?

• Prime

• Composite

​Did you know that all even numbers are composite EXCEPT the number 2?

​

​2 is the only even Prime Number!

​Tips from Mr.A

• ​When trying to determine if larger numbers are prime or composite, look at the digit in the ones place. If it's an even number or a 0, the number is most likely composite.

• ​Another strategy is to divide the number by 2, 3, 4 or 5. If it divides evenly with no remainders that number is composite. But if you get past dividing by 5 and you keep getting remainders, it's safe to say it is prime.

​You could also just memorize them...

​Your turn!

Multiple Choice

18

• Prime

• Composite

Multiple Choice

32

• Prime

• Composite

Multiple Choice

47

• Prime

• Composite

Multiple Choice

27

• Prime

• Composite

Multiple Choice

53

• Prime

• Composite

Multiple Choice

63

• Prime

• Composite

Poll

How would you rate your understanding of Prime and Composite numbers?

• 1- I have no idea what i'm doing.

• 2- Mas o menos, ahi la llevo. I still need help.

• 3- I am confident I can identify these with little or no help.

​No matter what you're doing, practice makes perfect.