I’m not Beth, but I’m bored so I’ll answer anyway. It depends on what style guide you’re using, but in Chicago style, used for most US fiction, most compound adjectives aren’t hyphenated after “to be,” but some “permanent compounds” that are listed in the dictionary (Webster’s 11th Collegiate is Chicago’s dictionary) are hyphenated. To make it more complicated, Chicago favors a sparser hyphenation style than that dictionary does, so some terms may be hyphenated in the dictionary but not in Chicago style. You can see their hyphenation table online here, which is a must-bookmark link for hyphen enthusiasts: http:///16/images/ch07_
, "sum, aggregate of a collection," from Anglo-French noumbre , Old French nombre and directly from Latin numerus "a number, quantity," from PIE root *nem- "to divide, distribute, allot" (related to Greek nemein "to deal out;" see nemesis ). Meaning "symbol or figure of arithmatic value" is from late 14c. Meaning "single (numbered) issue of a magazine" is from 1795. The meaning "musical selection" (1885) is from vaudeville theater programs, where acts were marked by a number. Meaning "dialing combination to reach a particular telephone receiver" is from 1879; hence wrong number (1886).
Number one "oneself" is from 1704 (mock-Italian form numero uno attested from 1973); the biblical Book of Numbers (, Latin Numeri , Greek Arithmoi ) so called because it begins with a census of the Israelites. Slang number one and number two for "urination" and "defecation" attested from 1902. Number cruncher is 1966, of machines; 1971, of persons. To get or have (someone's) number "have someone figured out" is attested from 1853. The numbers "illegal lottery" is from 1897, American English.
If your work must follow the rules of a specific style guide, understand that they all have rules for spelling out numbers that may differ slightly from the rules listed above. For example, MLA style indicates that writers may spell out numbers if they are not used too frequently in the document and can be represented with one or two words (., twenty-four, one hundred, three thousand ). APA style advises that common fractions (., two-thirds ) be expressed as words. A number of specific rules for spelling out numbers are outlined in section of the Chicago Manual of Style.