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.
To simplify a numerical fraction, I would cancel off any common numerical factors. For this rational expression (this polynomial fraction), I can similarly cancel off any common numerical or variable factors. The numerator factors as (2)(x); the denominator factors as (x)(x). Anything divided by itself is just 1, so I can cross out any factors common to both the numerator and the denominator. Considering the factors in this particular fraction, I get: Then the simplified form of the expression is: