The milky way galaxy has at least two hundred billion stars write half this number of stars in standard form

100,000,000,000 stars in half of the milky way galaxy

You have 2 sides that are 2 cms and you have 6 sides that are 1/2 cm and you have 4 sides that are 1 cm. the smallest sides are 1/2 the medium sized sides are 1 and the smallest are 1/2. so to find the perimeter you have to add them all up together so your answer will be 11 cm's