Question

There is a four digit number, which when written in reverse order, becomes 4 times itself. Find the number.

Answer 1

first write the no.in the form of 1000p+100q+10r+s, reverse it to get an equation in p,q,r,s.Since the second no. is four  times the first number,it is divisible by 4,so the last 2 digits of the new number (p,q) are divisible by 4,make some possible cases and it'll be easy to find a solution to that equation from the possible cases..the answer is 2178
and multiplied by 4 gives 8712.