7AU = 1 × 10^15 mm
7AU × (1.5 ×10^8 km/1 AU) = 1.0 × 10^9 km
1.0 × 10^9 km × (1000 m/1 km) = 1.0 × 10^12 m
1.0 × 10^12 m × (1000 mm/1m) = 1 × 10^15 mm
