Content
Startpage
 
Mathematic
   Golden Ratio
   Pi geometry
   Squaring the Square
   Magic square of 3. Order
   Magic square of 4. Order
 
Informatics
   Tangram
   Sudoku calculation
   N-Corner Frisbee
   L-game
   Logic Tower
 
Nature / physics
   Golf - GPS accuracy
   Golf - putting on a slanted green
   Golf - putting on a stepped green
   Corona pandemic 
 
Technique - Technology
   Thick optical lenses 
   Depth of field
   Excentric coaxial cable
   Force on live wires
   Gunn-oscillator 
   1 + 1 = ??? 
 
New: Corona pandemic