Prime and composite numbers intro
Learn about prime and composite numbers and practice identifying them.
Let's review factors
Factors are whole numbers that can be divided evenly into another number.
and are factors of because they can all be divided into without a remainder.
has four factors: , and .
Which of the following numbers are factors of ?
All numbers have and as factors.
Categories of numbers
We can divide almost all numbers into two categories: prime numbers and composite numbers.
Prime numbers are numbers with exactly factors.
A prime number's only factors are and the number .
is an example of a prime number. Its only factors are and . It is not evenly divisible by any other whole numbers.
Let's use pictures to visualize prime numbers.
Farmer Maxwell is making a chicken coop for his best egg laying hens. He has hens and is thinking about how he can arrange them. He wants to arrange the hens in equal sized groups.
The only possibility is to make row of hens.
An array of 7 hens arranged in 1 row of 7 hens.
Any other arrangements would not have the same number of hens in each row.
When there is only one possible way to divide a number into equal sized groups, that number is prime.
Is a prime number?
Composite numbers have more than factors.
is an example of a composite number. The factors of are and All of these numbers divide into evenly.
Let's use pictures to visualize composite numbers.
Farmer Maxwell is also inventing a new egg carton where he will store the eggs his hens lay. He wants each carton to hold eggs.
He could have row of eggs.
An array of 16 eggs arranged in 1 row of 16 eggs.
He could also have rows with eggs in each row.
An array of 16 eggs arranged in 2 rows of 8 eggs each.
Or he could have rows with eggs in each row.
An array of 16 eggs arranged in 4 rows of 4 eggs each.
Composite numbers have more than one way that they can be divided into equal groups.
Is a composite number?
does not fit into either category. It is neither prime nor composite.
Practice with prime and composite numbers
The numbers and are all
Prime number and composite number challenge
Use the clues given to solve the problems below.
Identify a prime number with in the ones place.
Want to join the conversation?
- Is 0 an even number or an odd(32 votes)
- Zero is an even number. In other words, its parity—the quality of an integer being even or odd—is even. ... Not only is 0 divisible by 2, it is divisible by every power of 2, which is relevant to the binary numeral system used by computers. In this sense, 0 is the "most even" number of all.(13 votes)
- Why is one not prime nor composite? What is it called?(11 votes)
- 1 is not composite because 1 does not have more than 2 factors, and all composite numbers have more than 2 factors.
1 is not prime because prime numbers are divisible by 1 and the number itself. 1 only contains itself and no other number. 1 belongs to its own unique category named "units."(17 votes)
- Is every even number a composite number because every even number has a factor of 2 except for 0 and 2.(7 votes)
- Yes, all even numbers except 2 and zero are composite numbers.
Zero is neither prime nor composite.(19 votes)
- Can all prime numbers be odd?(6 votes)
- 2 is the only even prime number because every other even number is divisible by 2. All other prime numbers are odd.(10 votes)
- Two is a prime number because prime numbers only have two factors,right?(7 votes)
- I love math who's like me?(8 votes)
- Eh, it's a medium.(1 vote)
- Is this important??(6 votes)
- yes this is important(4 votes)
- why is math called math?(5 votes)
- The word mathematics comes from Ancient Greek máthēma (μάθημα), meaning "that which is learnt", "what one gets to know", hence also "study" and "science". The word came to have the narrower and more technical meaning of "mathematical study" even in Classical times.-wikapieda(3 votes)
- Why prime number is created(5 votes)
- Is all even number numbers are composite(3 votes)
- Not all even numbers are composite, 2 is the only even number that is prime. 2 is a prime number because it is divisible only by 1 and itself, and 2 is an even number because it is evenly divisible by 2.(4 votes)