Subtract seconds from a time

You can subtract (or add) a number of seconds from a time using fractions.
Dates are represented as sequential whole numbers so 1 hour is equivalent to the fraction (1/24).
Times are represented as fractions based on there being 24 hours in a day.
1 Hour is 1/24 = 0.04166
1 Minute is 1/(24*60) = 1/1440
1 Second is 1/(24*60*60) = 1/86400

 A 1 =TODAY() = Tuesday 10 September 2024 2 =NOW() = Tuesday 10 September 2024 10:51:43 3 =A2-(200*(1/86400)) = Tuesday, 10 September, 2024 10:48 AM 4 =A2 - TIME(0, 0, 200) = Tuesday, 10 September, 2024 10:48 AM 5 =A2 - (40/1440) - (50/86400) = Tuesday, 10 September, 2024 10:10 AM 6 =A2- TIME(0, 40, 50) = Tuesday, 10 September, 2024 10:10 AM 7 =A2 - (3/24) - (15/1440) , (30/86400) = Tuesday, 10 September, 2024 07:36 AM 8 =A2 - TIME(3, 15, 30) = Tuesday, 10 September, 2024 07:36 AM

1 - Displays the current date. Custom format "dddd dd mmmm yyyy".
2 - Displays the current date and time. Custom format "dddd dd mmmm yyyy hh:mm:ss".
3 - Displays the current time minus 200 seconds.
4 - Displays the current time minus 200 seconds using the TIME function to return the correct decimal.
5 - Displays the current time minus 40 minutes and 50 seconds.
6 - Displays the current time minus 40 minutes and 50 seconds using the TIME function to return the correct decimal.
7 - Displays the current time minus 3 hours, 15 minutes and 30 seconds.
8 - Displays the current time minus 3 hours, 15 minutes and 30 seconds using the TIME function to return the correct decimal.
All these cells have been formatted with the custom number format "dddd, dd mmmm, yyyy hh:mm AM/PM".

Built-in Functions

NOW - The date serial number of the current system date and time.
TIME - The time as a decimal given an hour, minute, second.
TODAY - The date serial number representing today's date.