Question

anyone can solve then please
explain it step by step

Answer 1

$1nm = {10}^{ - 9} m \\ 4 \times {10}^{11} nm = 4 \times {10}^{11} \times {10}^{ - 9} m \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 4 \times {10}^{2} = 400m$

Answer 2

1nm =10^-9 m
4×10^11 nm =4×10^11×10^-9
=4×10^2
=400