Check your course syllabus to see which style the professor or teacher wants to use for your paper. If it is APA, list prices that are less than nine by spelling them out and using the word that indicates price, such as dollars or cents. Anything higher than nine should have a numeral.
Write prices when they begin a sentence in either style. If they are within a sentence and only contain two words, then write them out completely, such as "thirty-two" or "twelve hundred." For numbers larger than two words, use numeric figures. A good example is "132," as "one hundred thirty-two" is four words.
Use numerals for all prices that are listed in both MLA and APA styles if they are within the body of a sentence. If they come at the beginning of a sentence, then spell them out. APA style guides highly recommend never starting a sentence with numerals, if it can be helped.
Always list price figures with either a cent mark or a dollar sign. This makes it easier to assimilate when reading through a paper as opposed to spelled out monetary values, such as "dollars" and "cents."
Write out the full description of fractional prices, such as "one-half of $1,000,000." Never use numerals to spell out fractions in either APA or MLA style.
Express large figures with a word value, such as "$63 billion." The meaning of $63,000,000 is much harder to discern and will have the reader counting commas. Include the sign for the monetary value and spell out any numbers that are estimations above a million.