Historical clue formulations

• 61, in old Rome — 2018-10-01
• 61, in old Rome — 2010-12-14
• Virgil's 61 — 2010-11-01
• Middle year of Nero's reign — 2009-02-26
• Year in Nero's reign — 1997-07-27
• 10% of DCX — 1996-05-26