Several arc numbers appear throughout Homestuck.
- Homestuck began on 4/13/09, and 413 is the arc number for the B1 kids.
- Hivebent began on 6/12/10, and 612 is the arc number for the A2 trolls.
- Cascade, the conclusion of Act 5, was posted on 10/25/11, 1025 being the sum of 413 and 612.
- Act 6 started on 11/11/11. This number and several variations of it serve as the arc number for the B2 kids and the cherubs.
With the exception of 1025, they start off as dates. They tend to recur throughout the remainder of the story in various manifestations.