# Revisiting the Introductory Challenge

What’s arithmetic?  Here’s the complete answer—as it exists in one good source at present. (It will be different later.)

It’s an answer neither Sam nor Jessica’s mom could possibly have provided.

Here is the first paragraph from Wikipedia’s article, “Arithmetic”:

Arithmetic or arithmetics (from the Greek ἀριθμός arithmos, “number”) is the oldest and most elementary branch of mathematics. It consists of the study of numbers, especially the properties of the traditional operations between them — addition, subtraction, multiplication and division. Arithmetic is an elementary part of number theory, and number theory is considered to be one of the top-level divisions of modern mathematics, along with algebra, geometry, and analysis. The terms arithmetic and higher arithmetic were used until the beginning of the 20th century as synonyms for number theory and are, sometimes, still used to refer to a wider part of number theory. (http://en.wikipedia.org/wiki/Arithmetic)

Here is the definition from the Oxford English Dictionary:

The science of numbers; the art of computation by figures. (This dictionary also tells us that the first occurrence of the word “arithmetic” in written English took place in the year 1305!) http://public.oed.com/about/free-oed/