16 (55)5: (52)4 5.(55)2 =

16. $$\frac{(5^5)^5 : (5^2)^4}{5 \cdot (5^5)^2} = \frac{5^{5\cdot5} : 5^{2\cdot4}}{5 \cdot 5^{5\cdot2}} = \frac{5^{25} : 5^8}{5 \cdot 5^{10}} = \frac{5^{25-8}}{5^{1+10}} = \frac{5^{17}}{5^{11}} = 5^{17-11} = 5^6 = 15625$$

Ответ: 15625