- § 290. Ordinals are classes of serial relations
- § 291. Cantor's definition of the second class of ordinals
- § 292. Definition of
`ω` - § 293. An infinite class can be arranged in many types of series
- § 294. Addition and subtraction of ordinals
- § 295. Multiplication and division
- § 296. Well-ordered series
- § 297. Series which are not well-ordered
- § 298. Ordinal numbers are types of well-ordered series
- § 299. Relation-arithmetic
- § 300. Proofs of existence-theorems
- § 301. There is no maximum ordinal number
- § 302. Successive derivatives of a series

The Principles of Mathematics was written by Bertrand Russell, and published in in 1903. It is now available in the Public Domain.