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Using Prime Factorization to
    Identify Perfect Squares
What is Prime Factorization?

 Prime factorization is to write a composite
 number as a product of its prime factors.
 (www.northstarmath.com)




 Think back . . .

           A Prime Number is a whole number,
           greater than 1, that can be evenly divided
           only by 1 or itself.
Example : What are the prime factors of 12?

   We can figure this out using a factor tree.



                               12

                     6         x         2

              2     x      3        x 2
      The prime factors of 12 are 2, 2 & 3!
Example : What are the prime factors of 48?



                             48

                 6          x              8

            2    x     3    x     2        x       4

            2    x     3    x     2    x       2   x   2

  The prime factors of 48 are, 2, 2, 2, 2, & 3!
The prime factorization method can also be used to
demonstrate that a number is not a perfect square. From the
factor tree below, notice that none of the prime factors of 280
are present an even number of times.

                            280

               10            x            28

          2    x      5     x     2           x       14

          2    x      5     x     2     x         2   x    7

                    280 = 2 x 2 x 2 x 5 x 7
A perfect square has each
   distinct prime factor
occurring an even number
         of times.
Use the Prime Factorization Method to decide if 64 is a
perfect square.

                   64

          2        x        32

          2    x   2        x        16

          2    x   2    x   2        x        8

          2    x   2    x   2    x    2       x       4

          2    x   2    x   2    x    2   x       2   x   2

  64 = 2 x 2 x 2 x 2 x 2 x 2
  The factor 2 appears 6 times (an even number of time).
  We can say that 64 is a perfect square because . . .
A perfect square has each
   distinct prime factor
occurring an even number
         of times.