how many 8 digit nos are there the sum of whose digit is even?

• 43906250
  
  All are even => (5^8 - 5^7) numbers ------------(1)
  Here negative part 5^7 represents numbers with 0 as first digit
  
  Two are odd => 8C2*(5^4)*5^6 - 7C2*(5^2)*5^5 -------------(2)
  
  Four are odd => 8C4*(5^4)*5^4 - 7C4*(5^4)*5^3 -------------(3)
  
  Six are odd => 8C6*(5^6)*5^2 - 7C6*(5^6)*5 ----------------(4)
  
  All are odd => 5^8 -----------(5)
  
  => Total possibilities = (1) + (2) + (3) + (4) + (5)
  = 43906250 ways
• 11 years agoHelpfull: Yes(1) No(0)
• 9*10*10*10*10*10*10*5*5
  
• 11 years agoHelpfull: Yes(0) No(0)
• but ans is 45.10^6
• 11 years agoHelpfull: Yes(0) No(0)