#### Answer

345,600 sec

#### Work Step by Step

Use the unit fraction (24 hours)/(1 day) to change days to hours, next use the unit fraction (60 min )/(1 hr ) to change hours to min and last use the unit fraction (60 sec)/(1 min) to change min to sec. Notice how all the units divide out except second, which is the unit you want in the answer.
4 days * (24 hours)/(1 day) * (60 min )/(1 hr )* (60 sec)/(1 min) = 345,600 sec.