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How the Romans used their calendar - by Ian Reeves - our Treasurer

Latin scholars please look away now!

Special names were given to three days of each month: Kalendae (Kalends), Nonae (Nones) and Idus (Ides).
Kalendae - to the First of every month.
Nonae to the Fifth of January, February, April, June, August, September, November and December
Nonae also to the Seventh of March, May, July and October. I
dus to the Thirteenth of January, February, April, June, August, September, November and December
Idus also to the Fifteenth of March, May, July and October.
The day immediately before any of the three names was expressed as pridie.
The nones were always (according to the inclusive method of reckoning in use with the Romans) nine days before the Ides (nonus-ninth). All other dates were expressed as so many days before the next named day. Therefore counting both the date and the named day, the tenth was the sixth day before the fifteenth.
The formulae began with the words "ante diem" abbreviated to "a.d.". Eyes are beginning to cloud over, the writer is getting out of his depth so we will stay clear of the grammar.
The Roman months were designated by adjectives: Ianuarius, Februarius, Martius, Aprilis, Maius, Iunius, Quintilis (Iulius after 44BC), Sextilis (Augustus after 44BC), September, October, November, December.

We will take two months for examples to fit the others and stay with the abbreviations:

1 Kal Oct. 1 Kal. Nov
2 a.d. VI Non. Oct. 2 a.d. IV Non. Nov
3 a.d. V Non. Oct. 3 a.d. III Non. Nov
4 a.d. IV Non. Oct. 4 prid. Non. Nov
5 a.d. III Non. Oct. 5 Non. Nov
6 prid. Non. Oct. 6 a.d. VIII Id. Nov.
7 Non. Oct. 7 a.d. VII Id. Nov
8 a.d. VIII Id. Oct. 8 a.d. VI Id. Nov.
9 a.d. VII Id. Oct. 9 a.d. V Id. Nov.
10 a.d. VI Id. Oct 10 a.d. IV Id. Nov.
11 a.d. V Id. Oct. 11 a.d. III Id. Nov
12 a.d. IV Id. Oct. 12 prid. Id Nov.
13 a.d. III Id. Oct 13 Id. Nov.
14 prid. Id. Oct. 14 a.d. XVIII Kal. Dec
15 Id. Oct. 15 a.d. XVII Kal. Dec
16 a.d. XVII Kal. Nov. 16 a.d. XVI Kal. Dec
17 a.d. XVI Kal. Nov. 17 a.d. XV Kal. Dec.
18 a.d. XV Kal. Nov. 18 a.d. XIV Kal. Dec
19 a.d. XIV Kal. Nov 19 a.d. XIII Kal. Dec.
20 a.d. XIII Kal. Nov. 20 a.d. XII Kal. Dec.
25 a.d. VIII Kal. Nov 25 a.d. VII Kal. Dec.
30 a.d. III Kal. Nov. 30 prid. Kal. Dec.v
31 prid. Kal Nov. -

The Romans named their years according to the consul of the year or the number of years since the founding of the city of Rome (753 BC). For dates BC subtract from 754, for dates AD add to 753.

This information may well be on the internet in some shape or another. Those who have moved into the 21st century technology will no doubt tell us.