You would have to find the area of each side and add it all together if you were to solve it out it would be 45+25+32+25+35+35=394
1/100,000,000 , note that 100,000,000 = 10⁸ , then:
1/100,000,000 = 1/10⁸
Remember that 1/aⁿ = a⁻ⁿ
Hence 1/100,000,000 = 1/10⁸ = 10⁻⁸