Make a list of the multiples less than 50 and 
                circle the common multiples.
     1) 6, 8
           6:
              6     , 18, 24, 30, 36, 42, 48
               , 12
           8:                    , 48
              8     , 24, 32, 40
               , 16
      2) 4, 12
           4:                                   , 36    , 44, 48
               4,  8 , 12, 16, 20, 24, 28, 32       , 40
         12:
               12, 24, 36, 48
    Make a list of the first eight multiples and 
           circle the LCM.
   1) 3, 7
      3:
        3,  6 ,  9 , 12, 15, 18, 21, 24
      7:       , 42
        7, 14, 21, 28, 35
                      Which two are the 
   2) 2, 4,16         same?
      2:
        2,  4 ,  6 ,  8 , 10, 12, 14, 16
      4:
        4,  8 , 12, 16, 20, 24, 28, 32
    16:
        16, 32, 48, 64, 80, 96, 112, 128
 Use prime factorization to find the LCM.
           18               21
          2  9             3  7
           3   3
          233             37
                            
     Select all common factors once.
     Then select the remaining factors.
                    3   3
             LCM 2 7
                           
             LCM126
              
 Use prime factorization to find the LCM.
           45               48
          5  9             8   6
           3   3         2 4 2 3
                           2 2
          335         22223
                         
      Select all common factors once.
     Then select the remaining factors.
                     3352222
              LCM
              LCM720