By far the most popular and well-stocked category of used instruments is our selection of guitars, where we've got a huge variety of all the big names. Used Gibson Les Paul, pre-owned Fender Telecaster and secondhand Stratocaster guitars are commonly found within these pages, waiting for their new homes with players and collectors.
22/7 is a pretty decent choice for teaching 11-year-olds about fractions that are close to pi. 355/113 would be better, if you think they can remember numbers that big. And approxRational is fun. Exercise for the interested reader: implement an inverse to approxRational.
Posterior interventricular artery. In the coronary circulation, the posterior interventricular artery (PIV) or posterior descending artery (PDA) is an artery running in the posterior interventricular sulcus to the apex of the heart where it meets with the anterior interventricular artery. It supplies the posterior 1/3 of the interventricular septum.