4. (8 points) As shown in the figure, there are four circles of different sizes, with diameters from smallest to largest being $5$, $10$, $15$, and $20$ cm, respectively. Therefore, the sum of the areas of the shaded parts in the figure is $\qquad$ square cm. (Take $\pi$ as 3.14)
【Solution】Solution: According to the problem, we know:
The sum of the areas of the shaded parts is equal to the area of the largest circle. The radius of the largest circle is $20 \div 2=10$ (cm); the area is: $\pi r^{2}=100 \pi=314$ (square cm). Therefore, the answer is: 314