10 8 13 35 135 671 4007
(1) 8
(2) 671
(3) 135
(4) 13
(5) 35

• Wrong number in the series 2) 671
  
  10 x1 - 2 = 8
  
  8 x2 - 3 = 13
  
  13 x3 - 4 = 35
  
  35 x4 - 5 = 135
  
  135 x 5 - 6 = 669
  
  669 x 6 - 7 = 4007
  
  So wrong number in the series is 671
• 7 years agoHelpfull: Yes(0) No(0)