Find the missing number

4,7,13,21,_

• 4+3=7
  7+6=13
  13+9=21
  21+12=33
  
  Hence,missing number is 33
  
• 12 years agoHelpfull: Yes(1) No(10)
• 7-4=3
  13-7=6
  21-13=8
  
  therefore the diff. series becomes 3,6,8
  there is decrement of '1', in the adjacent 2 terms
  i.e., 6-3=3
  8-6=2
  9-8=1
  hence add 9
  therefore 21+9 = 30 ans.
  
• 10 years agoHelpfull: Yes(1) No(0)
• 1^2+2=3
  2^2+3=7
  3^2+4=13
  4^+5=21
  5^+6=31
• 9 years agoHelpfull: Yes(0) No(1)