Arithmetic Grade Four

Lesson Sixty-seven: Prime Factors

Certain numbers have no factors other than 1 and themselves. Here are the prime numbers you need to know for now: 

    1, 2, 3, 5, 7, 11, 13
There are a lot of prime numbers, but these are the ones that you should be aware of as a fourth grader. These are prime numbers because they have no other factors other than one and themselves: 

     NUMBER		FACTORS
   ---------------------------------
       1                  1
       2		  1, 2
       3                  1, 3
       5	 	  1, 5
       7                  1, 7
       11                 1, 11
       13                 1, 13
Most numbers have more than just two factors. Here are some examples: 

     NUMBER		FACTORS
   ---------------------------------
       4                  1, 2, 4
       6		  1, 2, 3, 6
      12                  1, 2, 3, 4, 6, 12
      15	 	  1, 3, 5, 15
      24                  1, 2, 3, 4, 6, 8, 12, 24
      33                  1, 3, 11, 33

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