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.
As with the Letter paper size A4 size paper is 6mm (0.2) narrow than US Legal paper, however unlike previously A4 has a smaller length than Legal paper by 59mm (2.3). Thus Legal paper is bigger in area than A4 by 0.015 square metres (0.18 square yards).