The pH of a 0.01 M weak acid ${\rm{HX}}\left( {{{\rm{K}}_a} = 4 \times {{10}^{ - 10}}} \right)$ is found to be 5. Now the acid solution is diluted with excess of water so that the pH of the solution changes to 6. The new concentration of the diluted weak acid is given as $x\,\, \times \,\,{10^{ - 4}}{\rm{M}}$ . The value of $x$ is ___________ (nearest integer)