1
   2
    3
     4
      5
       6
        7
         8
          9
          10
           11
            12
             13
              14
               15
                16
+)              :
-------------------
  123456790123456…


  1000000000 S = 1234567901.2345679012345679012345679……
-)           S =          1.2345679012345679012345679……
---------------------------------------------------------
   999999999 S = 1234567900
             S = 1234567900 / 999999999
	       = 100 / 81 (12345679で約分)