Subjects offered by the mathematics department are numbered 18.xy or 18.xyz. The two or three digits following the 18 contain information about the content and level of the subject.

Subjects with two digits, or whose third digit z is less than 5, are undergraduate subjects. If z is 5 or greater, the subject gives graduate level credit. (Several exceptions to this rule occur for specific majors. Non-math majors receive graduate credit for the following courses: 18.100, 18.101, 18.103, 18.112, 18.152, 18.354, 18.404, and 18.901. Math and certain other majors do not receive graduate credit for 18.075. Check the catalog for details. Subjects 18.089 - 18.099 are review, tutoring, and communication subjects that do not follow this rule.)

Subjects with first digit x = 0 are introductory. These provide the foundations for further study in many departments at MIT. Note that in some cases these subjects may not provide adequate background for deeper study of the material within the math department. Check the prequisites listed in the advanced courses.

If x is greater than 0, then x designates the mathematical area.