Consider the function S(n) defined on positive integers n by
S(n) = n - rev (n)
where rev (n) is the number with the digits of n reversed
For example,
S(71) = 71 - 17 = 54,
S(36) = 36 - 63 = -27.
The sum S(10) + S(11) + ... + S(95) equals
279
468
0
126
351

• s(10)+s(20)+s(30)+....+s(90)=405
  s(11)=s(22)=...s(88)=0
  s(12)=-9,s(21)=+9
  hence s(12)+s(21)=0,
  similarly s(13)+s(31)=0,.....except s(69),s(79),s(89)
  s(69)=-27,s(79)=-18,s(89)=-9
  hence total=405-27-18-9=351
• 10 years agoHelpfull: Yes(61) No(1)
• 351 is ans....
• 10 years agoHelpfull: Yes(6) No(1)
• 468 because in series there iis comman diff of 9 so calculating 1stand last term
  and using 9+(87-36)*9=468
• 10 years agoHelpfull: Yes(0) No(1)