Sunday Times Teaser 2794 – D-day
by Graham Smithers
Published: 10 April 2016 (link)
I have a particular digit in mind and I shall call it D. I have written down a number consisting of D digits in which the penultimate digit is D itself. If I move that penultimate digit to the left so that it becomes the first digit, then I get a new D-digit number that turns out to be D times the number I started with.
What is the D-digit number I started with?