There are 8 Ounces in a cup. Therefore the Tablespoon is 1/2 Ounce. A teaspoon is 1/3 of a tablespoon or 1/6 of an ounce. Remember this, 128 ounces in a gallon. 1/2 of a gallon is the next stop down = 64. 1/2 of that is a quart = 32 ounces. 1/2 of that is a pint = 16 ounces.
The difference between US Letter and Legal Paper sizes and international A4 is discussed here, however it is important to say that Letter is effectively the equivalent to A4 size in the USA.
A4 size paper is 6mm (0.2) are narrower than US Legal paper and has a smaller length ratio of 59mm (2.3); hence it is smaller than the Legal paper size. Legal paper is bigger in area than A4 by 0.015 square meters. Threats. They are used as a standard format in the administrations.