Kishore wrote a three-digit number abc, in the decimal system, on a board. Rajesh wrote the same number in base 7 and got the units digit as 5. Rakesh wrote the same number in base 6 and got the units digit as 4. Praneeth wrote the same number in base 5 and got the units digit as 3. If the number written by Kishore is in between 600 and 800, in which of the following ranges does the number abc lie?
a- 601-610
b- 661-670
c- 721-740
d- 611-630

• the number is 628
  it lie in range (d) 611-630
  solution
  let the number is divisible by 7,6,5
  lcm of them are = 210
  according to range given 600 - 800 the no. perfect divisible by 7,6,5 is 630
  now 630/7=90 , 630/6=105 ,630/5=126
  so no=7*89+5=628
  6*104+4=628
  5*124+3=628
  hence no is 628
• 11 years agoHelpfull: Yes(15) No(1)
• anki3121@gmail.com
  plz send me the material .. I m preparing for it.
• 11 years agoHelpfull: Yes(0) No(2)