When writing numbers in essays, it is important to follow the guidelines of the particular style guide used for the essay. Generally, when writing numbers, spell out numbers from one to nine and use numerals for numbers 10 and above. For larger numbers, it is acceptable to use a combination of numerals and words. For example, you could write “The population of the city is 5,000,” or “The population of the city is five thousand.” It is also important to be consistent throughout the essay. For example, if you start a sentence with a numeral, all other numbers in that sentence should also be expressed as numerals.