Bonjour,
1 m = 100 cm donc 85 000 cm = 85 000 ÷ 100 = 850 m
1 dam = 10 m donc 12 dam = 12 × 10 = 120 m
1 m = 10 dm donc 60 dm = 60 ÷ 10 = 6 m
1 km = 1 000 m donc 2 km = 2 × 1 000 = 2 000 m
1 m = 100 cm donc 700 cm = 700 ÷ 100 = 7 m
1 m = 1 000 mm donc 9 000 mm = 9 000 ÷ 1 000 = 9 m
3 dam 5 m = 3 × 10 + 5 = 35 m
9 000 m = 9 ÷ 1 000 = 9 km
20 000 dm = 20 000 ÷ 10 ÷ 1 000 = 2 km
1 000 m = 1 km
305 000 m = 305 km