there are number marked on pages of a book by mistake a same number is marked on pages twice and the sum of all page numbers is found to be 1000 now, find the number that may be marked twice

option
a) 40
b) 15
c) 25
d) None of these

• if n=43, sum=(43*44)/2=946
  if n=44, sum=(44*45)/2=990
  if n=45, sum=(45*46)/2=1035
  so no. of pages cant be 43 or 45
  no of pages=44, sum=990
  sum of pages=1000
  so 10 may marked twice
  ans 10
• 11 years agoHelpfull: Yes(1) No(0)
• if n=43, sum=(43*44)/2=946
  if n=44, sum=(44*45)/2=990
  if n=45, sum=(45*46)/2=1035
  so no. of pages cant be 43 or 45
  no of pages=45, sum=990
  sum of pages=1000
  so 10 may marked twice
  ans 10
• 11 years agoHelpfull: Yes(0) No(0)