According to Einstein's famous formula, the relationship between mass and energy can be written E = M ∙ c2, where E = energy in joules, m = mass in kilograms and c = speed of light in meters per second. Sweden's annual energy use amounts to approximately 1.35 ∙ 10 up tp 18J. Suppose that all this energy could be created by converting matter into energy. If so, how much mass would be needed to cover the country's annual energy use? The speed of light is 3 ∙ 10 up to 8 m / s