An electron is in the level n = 3 of hydrogen…

Step 1. Radius. $r_3 = 9 \times 0.0529\ \text{nm} = 0.476\ \text{nm}$. The speed is $7.30 \times 10^{5}\ \text{m/s}$.

Step 2. Wavelength. $\lambda = \dfrac{6.63 \times 10^{-34}\ \text{J s}}{9.1 \times 10^{-31}\ \text{kg} \times 7.30 \times 10^{5}\ \text{m/s}} = 9.98 \times 10^{-10}\ \text{m} = 0.998\ \text{nm}$.

Step 3. Count. The circumference is $2\pi \times 0.476\ \text{nm} = 2.99\ \text{nm}$. Then $\dfrac{2.99\ \text{nm}}{0.998\ \text{nm}} = 3.00$.