What should come in place of question mark (?) in the following numbers series?
4. 15 18 16 17 20 ?
(1) 23
(2) 22
(3) 16
(4) 18
(5) None of these

• 15+3=18 18-2=16 16+1=17 17+3=20 18+1=19
• 7 years agoHelpfull: Yes(2) No(0)
• 15-18=-3
  18-16=2
  16-17=-1
  17-20=-3 so 20+2=22
• 7 years agoHelpfull: Yes(0) No(2)
• 15-18=-3
  18-16=2
  16-17=-1
  17-20=-3 so 20-2=18
• 6 years agoHelpfull: Yes(0) No(0)
• 16 be the answer
• 6 years agoHelpfull: Yes(0) No(0)