0.01 moles of a weak acid HA $\left(K_a=2.0\times {10}^{-6}\right)$ is dissolved in 1.0 L of 0.1 M HCl solution. The degree of dissociation of HA is ______$\times {10}^{-5}$ (Round off to the Nearest Integer). [Neglect volume change on adding HA. Assume degree of dissociation <<1]