Prime or Composite Number Game
Number or Composite Number?
Related Resources
The resources listed below are aligned to the same standard, (4OA04) re: Common Core Standards For Mathematics as the Factors and multiplesGame shown above.
Find all factor pairs for a whole number in the range 1 to 100. Recognize that a ...
- (up to 251)
Target Game
Number lines
(small marks at 1s, large marks at intervals and no numbers)
(small marks at 1s, large marks at intervals and no numbers)
(small marks at 1s, large marks every 11 and no numbers)
(small marks at 1s, large marks every 12 and no numbers)
Worksheets
(2-page worksheet. Includes Guided Practice)
(2-page worksheet. Includes Guided Practice)
(3-page worksheet. Includes Guided Practice)
(3-page worksheet. Includes Guided Practice)Prime Numbers
The time is prime to learn about prime numbers--and in this BrainPOP movie, Tim and Moby are primed to teach you everything you need to know about these numerical building blocks! First, discover the one number that every prime number is divisible by, besides itself. Explore the work of ancient mathematicians like Euclid and Eratosthenes, who studied primes more than 2,000 years ago. See how every whole number greater than 1 is either a prime number itself or formed by multiplying prime numbers together. And get a glimpse of just how many prime numbers there are--and why the record for “biggest prime number ever” isn’t exactly a permanent one!
Learn More:Prime and Composite Numbers
Prime Numbers and Composite Numbers
A Prime Number can be divided evenly only by 1 or
And it must be a whole number greater than 1.
Example: 7 can only be divided evenly by 1 or 7, so it is a prime number.
But 6 can be divided evenly by 1, 2, 3 and 6 so it is NOT a prime number (it is a composite number).
Let me explain ...
can be divided up evenly, and some can't!
6 can be divided evenly by 2, or by 3:
Like this:
divided into 2 groups
divided into 3 groups
But 7 cannot be divided up evenly:
And we give them names:
When a number can be divided up evenly it is a Composite Number
When a number can not be divided up evenly it is a Prime Number
So 6 is Composite, but 7 is Prime.
explains it ... but there are some more details
Not Into Fractions
We are only dealing with whole numbers here! We are not going to cut things into
halves or quarters.
Not Into Groups of 1
OK, we could have divided 7 into seven 1s
(or one 7) like this:
But we could do that for any whole number!
So we should also say we are not interested in dividing by 1, or by the number itself.
It is a Prime Number when it can't be divided evenly by any number
(except 1 or itself).
Example: is 7 a Prime Number or Composite Number?
We cannot divide 7 evenly by 2 (we get 2 lots of 3, with one left over)
We cannot divide 7 evenly by 3 (we get 3 lots of 2,
with one left over)
We cannot divide 7 evenly by 4, or 5, or 6.
We can only divide 7 into
one group of 7 (or seven groups of 1):
So 7 can only be divided evenly by 1 or itself:
is a Prime Number
It is a Composite Number when it can be divided evenly
by numbers other than 1 or itself.
Like this:
Example: is 6 a Prime Number or Composite Number?
6 can be divided evenly by 2, or by 3, as well as by 1 or 6:
is a Composite Number
Sometimes a number can be divided evenly many ways:
Example: 12 can be divided evenly by 1, 2, 3, 4, 6 and 12:
1 & 12 = 12
2 & 6 = 12
3 & 4 = 12
a Composite Number
And note this:
Any whole number greater than 1 is either Prime or Composite
What About 1?
Years ago 1 was included as a Prime, but now it is not:
is not Prime and also not Composite.
We can also define a Prime Number using factors.
&Factors& are
numbers we multiply
another number.
And we have:
When the only two factors of a number are 1 and the number,
then it is a Prime Number
It means the same as our previous definition, just stated using factors.
And remember this is only about
(1, 2, 3, ... etc), not fractions or negative numbers. So don't say &I could multiply ½ times 6 to get 3& OK?
(the only factors are 1 and 3)
factors are 1,2,3 and 6)
Examples From 1 to 14
Factors other than 1 or the number itself are highlighted:
Can be Evenly
Divided By
Composite?
(1 is not considered prime or composite)
1, 2, 3, 6
1, 2, 4, 8
1, 2, 5, 10
1, 2, 3, 4, 6, 12
1, 2, 7, 14
So when there are more factors than 1 or the number itself, the number is Composite.
A question for you: is 15 Prime or Composite?
Why All the Fuss about Prime and Composite?
Because we can &break apart& Composite Numbers into Prime Number factors.
It is like the Prime Numbers are the basic building blocks of all numbers.
And the Composite Numbers are
made up of Prime Numbers multiplied together.
Here we see it in action:
2 is Prime, 3 is Prime, 4 is Composite (=2&2), 5 is Prime,
and so on...
12 is made by multiplying the prime numbers 2, 2 and 3 together.
12 = 2 & 2 & 3
The number 2 was repeated, which is OK.
In fact we can write it like this using the
12 = 22 & 3
And that is why they are called &Composite& Numbers because composite means &something made by combining things&
This idea is so important it is called .
There are many puzzles in mathematics that can be solved more easily when we &break up& the Composite Numbers into their Prime Number factors. A lot of internet security is based on mathematics using prime numbers.