Uncertainity in the position of an electron (mass = 9.1 × 10^–31 kg) moving with a velocity 300 m.s^–1, accurate upto 0.001 %, will be 
$\left(\mathrm{h}=6.63\times {10}^{-34}\mathrm{J}.\mathrm{S}\right)$

$∆\mathrm{x} =\frac{\mathrm{h}}{4\mathrm{\pi m} \times ∆\mathrm{v}}$

Mass = 9.1 × 10^–31 kg ; velocity =300 m.s–1 , accurate upto 0.001 %

so $∆\mathrm{v}$ =$\frac{300\times 0.001}{100}$;h =6.625$\times$10^-34

$∆\mathrm{x} =\frac{6.625 \times {10}^{-34}\times 100}{4\times 3.14\times 9.11\times {10}^{-31} \times 300\times 0.001}$ =19.30 $\times$10^-3

 = 1.93$\times$10^-2m