\[\boxed{\mathbf{2}\mathbf{.}\mathbf{142}}\]
\[\mathbf{Сочетательное\ свойство\ }\]
\[\mathbf{сложения:}\]
\[m + (n + k) = (m + n) + k =\]
\[= m + n + k.\]
\[m = 8946;\ n = 9637;\ \ \]
\[k = 10\ 308:\]
\[8946 + (9637 + 10\ 308) =\]
\[= 28\ 891\]
\[(8946 + 9637) + 10\ 308 =\]
\[= 28\ 891\]
\[8946 + 9637 + 10\ 308 = 28\ 891\]
\[28\ 891 = 28\ 891 = 28\ 891.\]
\[Равенство\ верно.\]