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@ @@Hßìÿa@ö§aI@†a‡Èÿa@óî‹Åä@

4n                                  [Mathcounts 1984] ( )

             5  7 35 2

140 ( )         138 ( )             130 ( ) 128 ( )

  . 5b 9        2a3 [AHSME 1967, MAӨ 2009] (                          )

                                               326

                a +b 9                                 5b 9

8( )               6( )                        4( )          2 ()

                20 [Mathcounts 2010] ( )

                .

110 ( )         108 ( )             106 ( ) 104 ( )

 18 ( )           564 × 825                                        (  )
                                                                      )
    9            14 ( )                        10 ( )        6 ()     )
                                                                      )
                   AB9              [Mathcounts 2010] (

                   7 BA7

86 ( )             62 ( )                      34 ( ) 31 ( )

         .12b × 51b ×16b = (3146)b             [AHSME 1967] (

                .sb sb = 12b + 15b +16b

44 ( )             42 ( )                      40 ( ) 38 ( )

         AMC12 AMC10                           [AMC10A 2003] (

                . AMC 10 + A MC 12 = 123422

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