Related Clues:

• 1,2,3, etc.
• Numbers
• 5 and 10, e.g.
• Mathematical figures
• See 6 Down
• 1, 2, 3, etc.
• Arabic characters
• Ran mules out one-by-one
• The starred answers' starts are Roman ones
• Items found on a face, miners taking ages left inside
• I and others, in old Rome