Concept:
De Broglie wavelength:
\[
\lambda = \frac{h}{mv}
\]
Step 1: Substitute values.
\[
m = 9.1 \times 10^{-31} \, \text{kg}, \quad v = 10^6
\]
\[
\lambda = \frac{6.63 \times 10^{-34}}{9.1 \times 10^{-31} \times 10^6}
\]
Step 2: Simplify.
\[
\lambda = \frac{6.63}{9.1} \times 10^{-9}
= 0.727 \times 10^{-9} \, \text{m}
\]
\[
\lambda = 0.727 \, \text{nm}
\]