Is it or is it not rational?

To some people, Recurring Numbers are a mystery. And to some they are plain long-winded.
But it's still possible to have fun with them.

Tip: Before you proceed, you may want to recap the definition of Rational Numbers.
http://www.heymath.com/heymath/

Qn: Are all recurring numbers rational?

If NO, how do we know??

If YES, how do we prove a recurring number is rational?
Use 0.15151515... to prove this.
Hint: Let 0.15151515... be x.