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.
A (letter) Letter sized paper measures 8.5 x 11 or 216 x 279 mm. This type of paper is the most common paper size in the U.S. Letter sized paper is used for a wide variety of printing needs including correspondence, signs, and other documents. Legal sized paper measures 8.5 x 14 or 216 x 236 mm. This type of paper is commonly used for legal documents such as contracts.