1,3,6,10,15,?

• 1 =1
  1+2 = 3
  3+3 = 6
  6+4 = 10
  10+5 = 15
  15+6 = 21
• 12 years agoHelpfull: Yes(5) No(0)
• in this series there is difference is
  3-1=2
  6-3=3
  10-6=4
  15-10=5
  x-15 should be equal to 6.where x is the number which we have to find out.hence x-15=6 i.e x=21 answer...
• 12 years agoHelpfull: Yes(1) No(0)
• ans=21
  1+2=3
  3+3=6
  6+4=10
  10+5=15
  15+6=21
• 12 years agoHelpfull: Yes(0) No(0)
• 1+2=3,
  3+3=6,
  6+4=10,
  10+5=15, so
  15+6=21,
• 12 years agoHelpfull: Yes(0) No(0)