Find missing term
1,3,3,6,7,9,13, ? ,21

• 12
  Alternate series 1, (+2) 3, (+4) 7, (+6) 13, (+8) 21 and
  3, 6, 9, 12, 15,....
• 9 years agoHelpfull: Yes(0) No(0)
• 12
  here we have two series one is 1,3,7,13 and 21 having difference 2,2+2,2+2+2 and 2+2+2+2
  second is 3,6,9 and 12
• 9 years agoHelpfull: Yes(0) No(0)
• 6_3=3
  9_6=3
  X_9=3
  X=12
• 9 years agoHelpfull: Yes(0) No(0)