80 370 ? 1550 2440 3530
a) 900 b) 840 c) 750 d) 860
a) None of these

• 860
  
  80 370 ? 1550 2440 3530
  370-80 = 290
  ____
  ______
  2440-1550 = 890
  3530-2440 = 1090
  
  So difference between terms is 290,490,690,890,1090.
  
  Hence 3rd term (?) should be 370+490= 860 ....option D
• 12 years agoHelpfull: Yes(26) No(2)
• 860
  10^2-20=80
  20^2-30=370
  30^2-40=860
  40^2-50=1550
  50^2-60=2440
  60^2-70=3530
• 9 years agoHelpfull: Yes(10) No(1)
• ans:option (d)
  first number is 80 second is obtained by adding 290 with the first one.
  third number is obtained by adding 490 with second number.like this keep on increasing the number by 200 and it to the previous number.
• 9 years agoHelpfull: Yes(2) No(0)
• if u see correctly we see that last term is 0 and 2nd last term is decreasing by 1...8,7, ,5,4,3,2.....s0 in ans 2nd last term is 6,so ans is 860(d)
• 9 years agoHelpfull: Yes(1) No(3)
• 860 is the ANSWER
  
  coz 80+290=370
  370+490=860
  860+690=1550....................
• 8 years agoHelpfull: Yes(1) No(0)
• 8+0=8
  3+7=10
  increse of two
  similarly 8+4=12
  
• 9 years agoHelpfull: Yes(0) No(2)
• 860 bcz in all number sbtract then come output is last 2 digit 90
• 8 years agoHelpfull: Yes(0) No(2)