The first felids emerged during the Oligocene, about 25 million years ago. In prehistoric times, a third subfamily, known as Machairodontinae, included the saber-toothed cats, such as the well known Smilodon. Other superficially cat-like mammals, such as the marsupial sabertooth Thylacosmilus or the Nimravidae, are not included in Felidae despite superficial similarities.
One of the key benefits to mashing out is lowering the viscosity of the liquid inside your mash tun. In other works, thinning it. This is especially important if you are using lots of non-barley grains such as wheat or rye (or pretzels). Also, many brewers tend to mash at a 1 quart per pound of grain ratio. Which, if not hot enough, could stick. Better put, is more likely to stick. And by making the mash more fluid what you are really doing is making the sugars in the wort more fluid. So, you will extract more of them; mashouts give you better efficiency.
How many potatoes and where to get them. You can grow your own, pick your own, or buy them at the grocery store. It takes about 10 to 14 pounds of potatoes to make 7 quarts; OR 5 to 8 pounds to make 9 pints. This works out to an average of 1 to 2 pounds per quart.