Divide 400 by 7. You get 1 as a remainder. now subtract one from 400 to get the greatest number less than 400 which is divisible by 7. <span>Now consider multiples of 7*1=7 is the 1st </span> <span>similarly 7*2=14 is the 2nd </span> <span>if their are n numbers than 7*n=399 </span> <span>u get n =57 which is the answer</span>