zamiana jednostek:    1/2 h = s 4 h = s 0,02 h = s 0,25 h =   s 1/2 min =   s 0,25 min =   s 60 s =   h 7200 s =   h 1800 s =   h 180 s =   h      / ---- krska ułamkowa  

1/2 h = 1800s 4 h = 14400s 0,02 h = 72s 0,25 h =   900s 1/2 min =  30 s 0,25 min =  15 s 60 s =   1/60h 7200 s =   2h 1800 s =  1/2 h 180 s =  1/30 h

1/2h = 1800s 4h = 14400s 0,02h = 72s 0,25h =   900s 1/2min =  30s 0,25min =  15s 60s =   1/60h 7200s =   2h 1800s =  1/2h 180s =  1/30h