Notice how much simpler it is in the expression above to multiply 400 ! 25 than it is to work with the more accurate 365 ! 24. These approximate values for the number of days in a year and the number of hours in a day are close enough for our purposes. Thus, in 70 years there will be (70 yr)(6 ! 105 min/yr) $ 4 ! 107 min. At a rate of 10 breaths/min