Numbers

Q. Are digits (e.g., 4, 8) appropriate for use in illustrations or diagrams to save space, even if they would be spelled out in text (e.g., four, eight)?

A. Highly appropriate! If you look at the “Illustrations and Tables” chapter of CMOS, you will see digits in the examples.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]