3 15 _ 51 53 159 161

• 
  Ans=17
  3,15,x,51,53,159,161
  difference between the two consecutive numbers is 2 ;exclude 3 here
  consider 17 here then
  17-15=2 and next number will be 17*3=51
  same process continued.
  53-51=2 and next number is 53*3=159
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  .
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  So ans=17
  
  
• 11 years agoHelpfull: Yes(12) No(1)
• 15+2=17*3=51
  51+2=53*3=159
  159+2=161
• 11 years agoHelpfull: Yes(8) No(1)
• 3*5=15,17*3=51,51*3=159
  therefore 17 is the answer
• 11 years agoHelpfull: Yes(0) No(2)