7,77,777,7777,77777,777777....
Find last 3 digits of sum of first 26 terms.

• at unit digit 7 would be coming 26 timing
  so, 26*7=182., 2 at unit place
  then 25*7=175+ (18 carry)=193
  then 24*7=187
  therefore answer is 732.,
  
• 9 years agoHelpfull: Yes(32) No(2)
• 7, 77, 777, 7777 ….to 26 terms.
  Sn=7+77+777+7777+……+to 26 terms
  =(7)[1+11+111+……+ to 26 terms]
  
  
  = (7/9) [(10-1) + (100-1) + (1000-1) +……...+ to n term]
  
  = (7/9) [10+100+1000+……... n terms – (1+1+1+1+…… n terms)
  
  = (7/9) [10+100+1000+………n terms –n]
• 9 years agoHelpfull: Yes(6) No(0)
• 7*26=182 so last digit is 2
  7*25+18=193 so 2nd digit is 3
  7*24+19=187 so 3rd digit is 7
  
  
  ans 732
• 9 years agoHelpfull: Yes(5) No(0)
• Ans is 732
  777*24+77+7=18732
• 9 years agoHelpfull: Yes(2) No(1)
• Ans is 732
• 9 years agoHelpfull: Yes(0) No(0)
• what formula have you used to get ans:732??
• 9 years agoHelpfull: Yes(0) No(0)
• unit digit : 2
  tens digit : 3
  hundreds digit:7
• 9 years agoHelpfull: Yes(0) No(0)
• 777
  77
  7
  ------
  861
• 9 years agoHelpfull: Yes(0) No(0)
• 7777
  777
  77
  -------
  247
• 8 years agoHelpfull: Yes(0) No(1)