111, 333, 666, and many other curious digits. What are Demlo numbers?

The Earth map used in the UN flag: 33 sectors A grid, probably representing parallels and meridians, divides the Earth in 33 sectors. Another special number is 11, 33 being a multiple of it. You probably wonder what  it means and what relation have these numbers with the Earth. 33 appears immediately as a particular number, being a palindrome. Moreover 3×3=9;  33×3=99… another palindromic digit I like is the number 12321. If you sum all digits, you’ll obtain[…]

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How to model your Earth with Google Sketchup

Sketchup is a 3D CAD software by Google. Many people do not consider it as a professional CAD but it has some good characteristics: –It is free: you can easily download it from sketchup.com; –It is simple to use and it enjoys of an excellent support on Internet with many tutorial videos; –It doesn’t require a workstation but you can reach satisfactory results even without having dedicated graphic board installed on your PC. When focusing the[…]

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