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 28 March 2023
2	=NOW() = Tuesday 28 March 2023 19:16:28
3	=A2-(200*(1/86400)) = Tuesday, 28 March, 2023 07:13 PM
4	=A2-TIME(0,0,200) = Tuesday, 28 March, 2023 07:13 PM
5	=A2-(40/1440)-(50/86400) = Tuesday, 28 March, 2023 06:35 PM
6	=A2-TIME(0,40,50) = Tuesday, 28 March, 2023 06:35 PM
7	=A2-(3/24)-(15/1440)-(30/86400) = Tuesday, 28 March, 2023 04:00 PM
8	=A2-TIME(3,15,30) = Tuesday, 28 March, 2023 04:00 PM

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.

Related Formulas

Subtract hours from a time
Subtract minutes from a time
Add seconds to a time