So 1662 – 1649 = 13, add 1 because 2 May is after 30 January, so the date falls in the 14th regnal year of Charles II. Example 3: 31 December 1695. This falls in the reign of William III alone (after Mary’s death), whose "first" regnal year is 1694; so 1695 – 1694 = 1, add 1 because 31 December is after 28 December, and also add 6 because the date is after Mary’s death (on 27 December), so the date falls in the "8th" year of his reign.