hii guys here is a doubt for me you are giving answers but can we remember as such
142857 so give us method to find the number tooo...............

heres my method for this

first we must get 9 in the last digit after six additions of same number meaning the last digit of the number multiplied by 7 must give 9 in the last position of resultant so it means only 7 is possible as last digit in the number....so we place 7 in last digit position...

number:_________7

now,we get carry 4 (7*7=49) to next digit so we need only 5 in next digit.......
to get 5 only 5 is possible(since 7*5=35)

number:_______57

now,we get carry 3(7*5=35) to next digit so we need only 6 in next digit...
to get 6 only 8 is possible(since 7*8=56)

number:______857

next,similarly carry:5 rdigit:4 nextdigit:2(7*2=14)

number:____2857

next,carry:1 rdigit:8 nextdigit:4(7*4=28)

number:__42857

next carry:2 rdigit:7 nextdigit:1(7*1=7)

number:142857