Let's calculate the de Broglie wavelength of an electron. We use the formula: wavelength (λ) = h / (m * v). Step 1: Identify the values. Planck's constant (h) = 6.626 x 10^-34 kg m²/s. Mass of electron (m) = 9.1 x 10^-31 kg. Let's assume the velocity (v) is 1,000,000 meters per second. Step 2: Multiply mass and velocity (momentum): 9.1 x 10^-31 * 1,000,000 = 9.1 x 10^-25 kg m/s. Step 3: Divide 'h' by this number: (6.626 x 10^-34) / (9.1 x 10^-25) = 7.28 x 10^-10 meters. This tiny number is the wavelength of the electron.