When we perform a 'digit slide' on a number, we move it unit's digit to the fornt of the no. For example the result of digi slide on 6471 is 1647.Let z be the smallest positive integer with 5as its unit digit such that the resultof a digit slideon the no.equal to 4times the no. how many digit will z have?
A)7
B)6
C)4
D)3

• as it is given that the number formed after digit slide is four times the original number with 5 at its unit place then keep on multiplying 5 with four until u get 5..
  5*4=20 so tens digit will be 0 carry 2
  now 0*4=0 carry=2 so digit at hundred place will be 2
  now 2*4=8 thousand place digit=8
  8*4=32 carry 3 ten thousand place digit will be 2
  2*4=8+ carry= 11 write 1 carry 1
  now finally 1*4=4 =carry =5
  
  hence number is 512820 after digit sliding
• 11 years agoHelpfull: Yes(81) No(2)
• 6 digits
  
  128205*4= 512820
• 11 years agoHelpfull: Yes(20) No(20)
• @pragat pal
  please explain the solution
  
• 11 years agoHelpfull: Yes(7) No(2)
• 5*4=20
  05*4=20
  205*4=820
  8205*4=32820
  28205*4=112820
  128205*4=512820
  Hence 6 ans
• 9 years agoHelpfull: Yes(7) No(1)
• let N be a number with x digits such that z=Nx10+5
  then the original no= Nx10+5
  and the digit shifted no= 5x(10^x)+N
  the equation can be made by 5x(10^x)+N= 4x(Nx10+5)
  then i used assuming N as 2...the equation gave a decimal number for N
  N=3...the equation gave a decimal for N
  N=5...the equation gave a whole number made of 5 digit for N
  hence the no is z=Nx10 +5 so total digit in z is 6
  
  hope u find this solution as satisfactory
• 10 years agoHelpfull: Yes(3) No(1)
• let N be a number with y no of digits
  such that z=N*10+5
  and the digit shifted no k= 5*(10^y)+N
  according to question k=4*z => 5*(10^y)+N= 4*(Nx10+5)
  then i used assuming N as 2...the equation gave a decimal number for N
  N=3...the equation gave a decimal for N
  N=5...the equation gave a whole number made of 5 digit for N
  hence the no is z=Nx10 +5 so total digit in z is 6
  
  kavima hope u get it this time....its just a hit and trial method....so bit difficult to express
• 10 years agoHelpfull: Yes(1) No(0)
• Hi Tapas..I couldnot understand ur explanation.Can u please explain one more time?
• 10 years agoHelpfull: Yes(0) No(0)