Dates

12.1How to key in a date#

Dates are typed as a number with the day and month before the point or after it. In month-first format (the default, M.DY) write the month, a point, the two-digit day and the four-digit year: 15 June 2026 is 6.152026. In day-first format (D.MY) write the day, a point, the two-digit month and the year: 15.062026.

Valid dates run from 15 October 1582 to the year 4046. An impossible date such as 30 February gives Error 8.

See also Display format and settings: Choose the date format

12.2Find the days between two dates#

Key in the earlier date, press ENTER, key in the later date, and press gΔDYSEEX (ΔDYS). X shows the actual number of days. Y shows the number of days on a 30/360 basis (twelve 30-day months). Press x⇄y to see Y.

Example 12.1

Days from 15 June 2026 to 25 December 2026

1. Key in 6.152026, ENTER, 12.252026 and press g, ΔDYS.

   6.152026ENTER12.252026gΔDYSEEX

Example 12.2

The 30/360 count of the same period

1. Press x⇄y.

   6.152026ENTER12.252026gΔDYSEEXx⇄y

Example 12.3

A non-leap year

1. 1 Jan 2025 to 1 Jan 2026.

   1.012025ENTER1.012026gΔDYSEEX

Example 12.4

A leap year

1. 1 Jan 2024 to 1 Jan 2025.

   1.012024ENTER1.012025gΔDYSEEX

12.3Add days to a date#

Key in the date, ENTER, then the number of days (negative to go back), and press gDATECHS (DATE). The display shows the new date and a number for the day of the week: 1 is Monday and 7 is Sunday. The new date is also in X as a date number.

Example 12.5

193 days after 15 June 2026

1. Key in 6.152026, ENTER, 193 and press g, DATE.

   6.152026ENTER193gDATECHS

Example 12.6

193 days before 25 December 2026

1. Key in 12.252026, ENTER, 193, CHS, then g, DATE.

   12.252026ENTER193CHSgDATECHS

Example 12.7

A leap day

1. One day after 28 February 2024.

   2.282024ENTER1gDATECHS

12.4Use day-first dates#

Press gD.MY4 (D.MY) to key in dates day first. Press gM.DY5 (M.DY) to return to month first.

Example 12.8

Days between in day-first format

1. Press g, D.MY. Key in 15.062026, ENTER, 25.122026 and press ΔDYS.

   gD.MY415.062026ENTER25.122026gΔDYSEEX

Example 12.9

Add days in day-first format

1. The result shows day first.

   gD.MY415.062026ENTER193gDATECHS

12.5Date errors#

Example 12.10

A date that does not exist

1. 30 February 2026 gives Error 8.

   2.302026ENTER1gDATECHS

Example 12.11

A month that does not exist

1. The 13th month gives Error 8.

   13.012026ENTER1gDATECHS