Express the order of magnitude of seconds in a day.
The number of seconds in a day would be
= number of seconds in a minute X number of minutes in an hour X number of hours in a day
= 60 x 60 x 24 seconds
or
it will be
1 day = 86400 seconds
in terms of order of magnitude
1 day = 8.64 x 104 secs ~ 105 secs
[here 8.65 ~ 10]