3,15,X,51,53,159,161.
Find X.

• i think, its 3,5,15,17,51,53...
  coz 3+2 =5 then 5*3=15, 15+2=17, 17*3=51, 51+2=53 and so on.
• 14 years agoHelpfull: Yes(13) No(0)
• 17
• 14 years agoHelpfull: Yes(6) No(2)
• 17
• 14 years agoHelpfull: Yes(4) No(1)
• 2 bcoz difference between consecutive terms in pair is 2
  53-51=2,161-59=2
• 14 years agoHelpfull: Yes(0) No(6)
• 3*3+2=11
• 14 years agoHelpfull: Yes(0) No(4)
• it consists of two series
  3,x,53,161 nd 15,51,159 i.e 3*5 +2 ,17*3+2 nd so on.....
• 13 years agoHelpfull: Yes(0) No(0)
• X = 17 but for X to be 17 there should be a number 5 between 3 & 15 to follow the pattern of the question.
  the pattern is the difference between the pairs is 2 so to follow this pattern there must be 5 between 5 and 15 so the series would be 3,5,15,17, 51,53,159,161....
  5-3=2
  17-15=2
  53-51=2
  161-159=2
• 8 years agoHelpfull: Yes(0) No(0)