In the following sum,"?" stands for which digit?

?+1?+2?+?3+?1=21?

a)4
b)6
c)8
d)none of these

• Nice Question..
  answer will be 8
  
  _+ 1_ + 2_ +_3 + _1 =21_
  put the no. 8 in the blanks
  it will be
  
  8 + 18 + 28 + 83 + 81 = 218
  so answer will be 8
• 10 years agoHelpfull: Yes(3) No(0)
• we know that if we have 2 digit number xy than it is reperesented by 10*x+y
  
  so apply the same concept here
  
  x+(10+x)+(20+x)+(10*x+3)+(10*x+1)=200+10+x
  
  x=8
• 10 years agoHelpfull: Yes(1) No(0)
• '?'=8,
  8+18+28+83+81=218
• 10 years agoHelpfull: Yes(0) No(0)
• x+10+x+20+10*x+3+10*x+1=210+x
  now solving for x we get x=8
  
• 10 years agoHelpfull: Yes(0) No(0)
• Ans : 8
  x+1x+2x+x3+x1=21x
  
  unit digit addition
  x+x+x+3+1=x
  3x+4=x
  sub x=4 or 6 or 8 given in options
  3(8)+4="8" with a remainder of 2
  
  ten's digit addition
  1+2+x+x+2(remainder)=21
  
  so x=8 which gives 21
  
  ans : 8
  
• 10 years agoHelpfull: Yes(0) No(0)