A big drop is formed by coalescing 1000 small identical drops of water. If $E_1$ be the total surface energy of 1000 small drops of water and $E_2$ be the surface energy of single big drop of water, the $E_1: \mathrm{E}_2$ is $\mathrm{x}: 1$ where $\mathrm{x}=$ $\_\_\_\_$ .
