Triangular Numbers https://www.mathematische-basteleien.de/triangularnumber.htm
You can arrange them to n(n+1)/2 pairs. n+1 horizontal lines also have n(n+1)/2 pairs
Dein Suchergebnis zum Thema: have
Paper Banger https://www.mathematische-basteleien.de/banger.htm
You have a similar sound if you clap your hands once. ……
Domino Puzzles https://www.mathematische-basteleien.de/dominos.htm
These are the squares, which the dominos have.
Paper Basket https://www.mathematische-basteleien.de/basket.htm
(If you have no practise, you should pre-fold by several halvings.) 10 …
Spirograph https://www.mathematische-basteleien.de/spirographs.htm
In the end you have to use both trigonometric formulas. Result: ……
Fünfstrahlige Figuren https://www.mathematische-basteleien.de/fuenfstrahlig.htm
Links ein Beispiel Kepler-Poinsot-Körper "All four (Kepler-Poinsot Polyhedra) have
Cuboctahedron https://www.mathematische-basteleien.de/cuboctahedron.htm
Opposite areas have the same colours.
Sonobe Star https://www.mathematische-basteleien.de/sonobestar.htm
You just have to make sure that not five pyramids but four pyramids form a wreath
Paper Boat https://www.mathematische-basteleien.de/paper_ship.htm
You have formed the well known hat. 9 …