Number of ways $$=$$ coefficient of $$x^{16}$$ in $$\left(x+x^2+\ldots+\right.$$ $$\left.x^6\right)^4$$

$$=$$ coefficient of $$x^{16}$$ in $$\left(1-x^6\right)^4(1-x)^{-4}$$

$$=$$ coefficient of $$x^{16}$$ in $$\left(1-4 x^6+6 x^{12} \ldots\right)(1-x)^{-4}$$

$$={ }^{15} C_3-4 \cdot{ }^9 C_3+6=125$$