Page 59 - Numbertheory

@ @óáÕÜa@óïÝibÔ@

5+b +9 9 :

.b = 4 5b 9

.9
.

20 [Mathcounts 2010] ( )
.

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

()

2 + 4 + 6 + ... + 38 + 40 = 420 x

.

x + (x + 2) + (x + 4) + (x + 6) = 420

. x = 102 . 4x = 408

. x + 6 = 108

18 ( ) 564 × 825 10 ( ) ()
6 ()
14 ( )

:( )

٤٦