The fifth hyperfactorial: 5⁵×4⁴×3³×2²×1¹=86400000 milliseconds is exactly 1 day
It was useful for sailors to be able to divide the day into shifts, so our day is the most divisible number of hours long.<p>1 x 2 x 3 x 4<p>That way you could have half days, quarter days, or third of days.<p>An hour is divided into 60 minutes: 3 x 4 x 5<p>The word "second" means a "second division by 3 x 4 x 5"