Bonjour,
1 cm = 1/100 m = 1/10² m = 10⁻² m
0,01 cm = (10⁻²)/100 m = (10⁻²)/10² m = 10⁽⁻²⁻²) m = 10⁻⁴ m
1 dm = 1/10 m = 1/10¹ m = 10⁻¹ m
0,000000001 m = 10⁻⁹ m
1 dam = 10 m
1 000 km = 10³ km = 10³ × 1 000 m = 10³ × 10³ m = 10³⁺³ m = 10⁶ m
1 nm = 10⁻⁹ m donc 0,2 nm = 0,2 × 10⁻⁹ m = 2 × 10⁻¹⁰ m
1 μm = 10⁻⁶ m donc 0,0005 μm = 0,0005 × 10⁻⁶ m = 5 × 10⁻¹⁰ m
et, comme il s'agit de révisions, je te laisse continuer....