The second is the basic unit of time. These seconds make minutes, minutes, make hours, and hours together make day and so on... Here we bring a calculation of seconds in a 24-hour day.
One day has 24 hours, one hour has 60 minutes and one minute has 60 seconds, so 24 hours/day times 60 minutes/hour times 60 seconds/minute is equal to 86400 seconds/day:
1 day = 24 hours/day × 60 minutes/hour × 60 seconds/minute = 86400 seconds/day
There are 86400 seconds in a 24-hour day.