A number followed by an exclamation point means multiplying it by each whole number below it until one.

3! = 3*2*1 = 6
5! = 5*4*3*2*1 = 120
10! = 10*9*8*7*6*5*4*3*2*1 = 3,628,800

3,628,800 seconds / 60 = 60,480 minutes
1008 hours
42 days
6 weeks