Try out this riddle: If you could double over a piece of normal notebook paper 42 times, how thick would it be?
원문출처 : https://www.cnn.com/2020/05/28/health/coronavirus-science-education-wellness-scn/index.html
원문출처 : https://www.cnn.com/2020/05/28/health/coronavirus-science-education-wellness-scn/index.html