7. A classmate typed the following several circles on the computer (where 〇 represents a solid circle, and $\bigcirc$ represents a hollow circle): If these several circles are copied in sequence to form a series of circles, then among the first 2008 circles, there are $\qquad$ hollow circles.
7. The proposition introduces “copying”, linking an important function in computer operations with a significant concept in mathematics, “periodicity”. The problem states that 2008 circles are arranged in a “segment” with “periodic” changes. Each “segment” of 27 circles contains 6 hollow circles. There are 74 such “segments” in 2008 circles, plus the first 10 circles, resulting in a total of $74 \times 6+3=447$ hollow circles.