Réponse:
bonjour
1km=1000m; 1h=60min=3600s; 1min=60s
423 km en m
=>430000m
78,5 dam en cm
=>785cm
0,00085 hm en mm
=>85mm
3h en min
=>180min
5 min en s (60×5)
=>300s
3 h en s (3×3600)
=>10800s
4h22min en s (4×3600+22×60)
=>15720s
90 km/h en m/s (90 km /h = 90 000 m : 3600 s =25 m / s)
=>25m/s
25,6 m/s en km/h
=>92,16km/h
1 m/s en km/h
3,6km/h
