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.
    Some other possibilities for your question:     1. area/circumference = r/2     2. circumference/area = 2/r     3. Ratios are fractions, and pi is a ratio between the circumference of a circle and its diameter.ractions consist of two numbers: a numerator (which is above the line) and a denominator (which is below the line). So to work out the square root of a fraction you find the square root of the numerator and put it above the square root of the denominator.