Kids Math
Prime Numbers


Skills needed:
Multiplication
Division
Addition
Whole numbers
What is a prime number?
A prime number is a whole number with exactly two factors, itself and 1.
Okay, maybe that's a bit hard to understand. Let's take a look at some examples:
The number 5 is a prime number because it cannot be divided evenly by any other numbers except for 5 and 1.
The number 4 is not a prime number because it can be divided evenly by 4, 2, and 1.
Is the number 13 a prime number?
It can't be divided by 2, 3, 4, 5, 6, 7, 8....etc. Only by 1 and 13. Yes, 13 is a prime number.
Is the number 25 a prime number?
It can't be divided by 2, 3, 4....true. Ah, but it can be divided by 5, so it is not a prime number.
Here is a list of the prime numbers between 1 and 100:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
Take a look at a few of them and see if you can figure out any other number that they can be divided by other than the number itself or the number 1. (hint: we promise the answer is "no" and they are, therefore, prime numbers).
Some tricks to prime numbers:
 The number 1 is not considered a prime number.
 All even numbers greater than 2 are not prime numbers.
 There are an infinite number of prime numbers.
Fun Facts about prime numbers
Prime numbers are often used in cryptography or security for technology and the internet.
The number 1 used to be considered a prime number, but it generally isn't anymore.
The largest prime number known has around 13 million digits!
The Greek mathematician Euclid studied prime numbers in 300BC.
The number 379009 is a prime number. It also looks like the word Google if you type it into a calculator and look at it upside down!
Here is a interesting sequence of prime numbers in which all of the digits have circles in them:
 6089
 60899
 608999
 6089999
 60899999
 608999999
Advanced Math
The fundamental theorem of arithmetic says that any number can be expressed by a unique product of prime numbers.
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