One person mentioned that he bought salted butter because of its keeping
properties. While it's true that salted butter does keep longer, it's also
possible to keep unsalted for a greater period of time simply by freezing
it--I do this all the time, because I stock up when there's a good sale on
butter. If you take the precaution of putting the butter, still in its
original packaging, in a zippy bag or a tightly sealed plastic container
(so it doesn't pick up odors), it will keep for up to six months in your
refrigerator freezer, and even longer in a deep freeze.
Also, in response to the person who asked for avoirdupois to metric
conversions on liquids, water in specific, a teaspoon is 5 milliliters, a
Tablespoon is 15mL, an ounce 30mL, a cup is approximately 240mL. And, as a
milliliter of water weighs exactly 1 gram, those conversions are not at all
difficult--it's one-for-one.