There are 24 times 7 times 3, or 504 hours in three weeks. Multiply by 60 to get minutes, 30240, and by 60 again to get seconds, 1814400.
3024000 seconds
1512000 seconds
1209600 seconds
28 weeks = 16,934,400 seconds.
There are 1,814,400 seconds in 3 weeks.
7 weeks = 4,233,600 seconds.
There are 7,257,600 seconds in 12 weeks.
6 weeks = 3,628,800 seconds.
0.000458 weeks = 276.9984 seconds.
16 weeks = 9,676,800 seconds.
There are 1,209,600 seconds in 2 weeks.