4,2,5,9,5,11,13,7,16,17,9,?

• 4,2,5,9,5,11,13,7,16,17,9,?
  see the triplets
  4,2,5 -> diff b/w 4,5 = 1
  9,5,11 -> diff b/w 9,11 = 2
  13,7,16 -> diff b/w 13,16 = 3
  17,9,21 -> diff b/w 17,21 = 4
  so the answer should be 21
• 12 years agoHelpfull: Yes(82) No(6)
• answer is 21
  break the series in three series as following-
  4,9,13,17
  2,5,7,9
  5,11,16,?
  common diff is -5,-4,-4 in 1st
  common diff is +3,+2,+2 in 2nd
  common diff is -6,+5, x in 3rd ...so x must be +5
  
  so, next term = 16+5 = 21
• 12 years agoHelpfull: Yes(23) No(6)
• answer is 21..
  4+2=6-1=5
  9+5=14-3=11
  13+7=20-4=16
  17+9=26-5=21..
  Hence the series can be continued like this way...
• 12 years agoHelpfull: Yes(10) No(16)
• Ans is 21.
  
  logic is
  (4,2,5)
  4-2=2+3=5
  (9,5,11)
  9-4=5+6=11
  (13,7,16)
  13-6=7+9=16
  
  (17,9,?)
  17-8=9+12=21
  
  
• 10 years agoHelpfull: Yes(10) No(2)
• The answer is 21.
  
  Break the series into 4 parts
  4 2 5
  9 5 11
  13 7 16
  17 9 ?
  and work vertically as follows.
  
  1st v-line 4+9=13, 13+[4]=17;
  2nd v-line 2+5=7, 7+[2]=9;
  3rd v-line 5+11=16, 16+[5]=21.
  
• 10 years agoHelpfull: Yes(7) No(0)
• 4-2=2, 9-5=4, 13-7=6, 17-9=8
  5+6=11, 11+5=16, 16+4=20. ans=20
• 10 years agoHelpfull: Yes(2) No(11)
• 21,taking 3 digits(4,2,5)(9,5,11),(13,7,16),(17,9,?(21))
  4+1=5,
  9+2=11,
  13+3=16,
  17+4=21.
• 8 years agoHelpfull: Yes(2) No(0)
• ANS 21
  
  4,2,5 -> diff b/w 4,5 = 1
  9,5,11 -> diff b/w 9,11 = 2
  13,7,16 -> diff b/w 13,16 = 3
  17,9,21 -> diff b/w 17,21 = 4
  
• 8 years agoHelpfull: Yes(0) No(0)
• Break the series into 4 parts
  4 2 5 => (2+2,2,2+3)
  9 5 11 => (4+5,5,5+6)
  13 7 16 => (6+7,7,7+9)
  17 9 ? => (8+9,9,9+12)
  
  so ans is 21
• 7 years agoHelpfull: Yes(0) No(0)