today IBM qns on series i got.....
9, 3, 6, 21, 9, 12, 33, 15, 18, ?
3, 7, 10, 8, 4, 12, 0, 5, 5, 3, 2, ?
7, -35, -34, -3, 15, 16, ?
12, 3, 15, 14, 6, 19, 16, 9, 23, 18, 12, ?
7,-14,-4,15,-30,-20,-21...?
4,2,4,8,6,8,16,..

• 9, 3, 6, 21, 9, 12, 33, 15, 18, ?
  3*1=3 and 3*2=6 so 3+6=9 and this is the first term. similarly 3*3=9 and 3*4=12 so 9+12=21. 3*5=15 and 3*6=18 so 15+18=33 finally 3*7=21 and 3*8=24 so 21+24=45.
  So 45 is the answer.
  2. 3, 7, 10, 8, 4, 12, 0, 5, 5, 3, 2, ?
  If we consider the first two terms that is 3 , 7 and 3+7=10. similarly 8+4=12,0+5=5,so 3+2=5 which is the answer.
• 10 years agoHelpfull: Yes(26) No(2)
• 12, 3, 15, 14, 6, 19, 16, 9, 23, 18, 12, ?
  
  (12+3)=15
  
  (14+6)-1=19
  
  (16+9)-2=23
  
  so ans is
  
  (18+12)-3=27
  
• 10 years agoHelpfull: Yes(21) No(0)
• 4,2,4,8,6,8,16,?
  (4,2,4),(8,6,8),(16,?)
  4-2=2
  8-2=6
  16-2=14
• 10 years agoHelpfull: Yes(17) No(2)
• 5.
  (7,-14,-4)= 7*-2=-14, -14+10=-4
  (15,-30,-20)= 15*-2=-30, -30+10=-20
  (-21,?,?)= -21*-2=42(ans)
  
• 10 years agoHelpfull: Yes(13) No(0)
• 7, -35, -34, -3, 15, 16, ?
  
  (7*-5)=-35
  -35+1=-34
  -3*-5=15
  15+1=16
  
  so take 7,-3,x
  we get -3 from 7 by doing 7-10=-3
  do the same for getting x
  -3-10=-13
  ans -13
  
• 10 years agoHelpfull: Yes(9) No(4)
• 3, 7, 10, 8, 4, 12, 0, 5, 5, 3, 2, ?
  
  3+7=10
  8+4=12
  0+5=5
  .
  .
  .
  3+2=5
• 10 years agoHelpfull: Yes(8) No(0)
• 7,-14,-4,15,-30,-20,-21...?
  
  (7,-14),-4,(15,-30),-20,(-21,x)
  
  ans -21*2= -42
  
• 10 years agoHelpfull: Yes(6) No(16)
• 3+6=9
  9+12=21
  15+18=33
  
  3*1=3
  3*2=6
  
  3*3=9
  3*4=12
  
  3*5=15
  3*6=18
  
  now, 3*7=21 and 3*8=24
  21+24=45(ans.)
  
  
• 10 years agoHelpfull: Yes(5) No(0)
• for 9, 3, 6, 21, 9, 12, 33, 15, 18, ?
  
  can be seen as
  9, (3,6),21,(9,12),33,(15,18),?
  i.e ignore the num in brackets
  
  9,21,33,?
  difference b/w two successive num is 12
  so ans is 33+12=45
  
  
• 10 years agoHelpfull: Yes(4) No(1)
• 4,2,4,8,6,8,16,..
  
  (4,2,4),(8,6,8),(16,?,?)
  2*3=6
  
  therefore ans is 6*3=18
• 10 years agoHelpfull: Yes(4) No(16)
• 3,7,10,8,4,12,0,5,5,3,2,?
  3+7=10,8+4=12,0+5=5,3+2=5 so ans:5
• 10 years agoHelpfull: Yes(3) No(0)
• 9,3,6,21,9,33,15,18
  
  3*3 = 9
  3*7 = 21
  3*11 = 33
  
  so the diff is 4 next is 15
  so next no. is 3*15 = 45
• 10 years agoHelpfull: Yes(3) No(1)
• 6) (4,2,4)(8,6,8)(16,-)
  1st term of each group- 4*2=8, 8*2=16
  2nd term of each group- 2*3=6, 6*3=18
  3rd term of each group- 4*2=8, ......
  so, ans is 18
  
• 10 years agoHelpfull: Yes(2) No(6)
• we divide it into 3 group : (9,6,3),(21,9,12),(33,15,18) next three term we dont know...observe these 3 group
  last 2 term is the multiple of 3 so next last two term are 21,24
  first term = sum of last two terms so 21+24= 45
  
  
• 7 years agoHelpfull: Yes(0) No(0)