What are the even-month doomsday dates?

The "doubles": 4/4, 6/6, 8/8, 10/10, 12/12 — each even month has its doomsday on the day equal to the month number.

• April → 4/4
• June → 6/6
• August → 8/8
• October → 10/10
• December → 12/12

All five fall on the year's doomsday. They're the easiest to recall — month number repeated — so they're usually your go-to anchor for the second half of the year.