#13 Hundred(s) ... from old math terms notes.

 Hundred is from the German root hundt. The quantity that it represents has not been consistent over the years and has ranged from its present value, 100, to 112, 120, 124, and 132 at different times in different areas. The remnants of these old measures still persist in the hundredweight of some countries representing 112 or 120 pounds, depending on the country.

The hundredweight has had many values. In England in around 1300, different "hundreds" (centum in Medieval Latin) were defined. The Weights and Measures Act 1835 formally established the present imperial hundredweight of 112 lb.

The United States and Canada came to use the term "hundredweight" to refer to a unit of 100 lb. This measure was specifically banned from British use—upon risk of being sued for fraud—by the Weights and Measures Act 1824 but in 1879 the measure was legalised under the name "cental" in response to legislative pressure from British merchants importing wheat and tobacco from the United States.*Wik

 A hundred has also been used to represent an area of land equal to 100 hides (of cattle?). The measure of area was frequently used in colonial US, and parts of England in place of "Shire" or "Ward".

Meaning "division of a county or shire with its own court" (still in some British place names and U.S. state of Delaware) was in Old English and probably represents 100 hides of land. The Hundred Years War (which ran intermittently from 1337 to 1453) was first so called in 1874.    Older blacksmiths' anvils are often stamped with a three-digit number indicating their total weight in hundredweight, quarter-hundredweight (28 lb, abbreviated qr), and pounds. Thus, an anvil stamped "1.1.8" will weigh 148 lb (112 lb + 28 lb + 8 lb).[*Wik ]

 A curious custom related to one hundred as a unit of land occurs in England when a member of the House of Commons wishes to resign his seat, which is illegal. An MP accepts stewardship of the "Chiltern Hundreds", an area of chalk hills near Oxford and Buckingham, and effects his release from Parliament.