Darcourse

Joke!!!

Two Chinese brothers, Wong A. and Wong B., decide to set up a paint factory 'TuWongs'. They only sell the darker shades. Why?

Because TuWongs don't make a white!

Lexical

What are called 00101101 and 3,5,6,8?

Coupon collection

An album has 100 places. A sticker pack of 5 costs $1. Individual named stickers cost $10 each. When it is wise to buy individual stickers instead of packs?

Pythagoras puzzle

If $a^{2}+b^{2}=c^{2}$ and $d^{2}+e^{2}=f^{2}$, can $a^{2}+d^{2},b^{2}+e^{2},c^{2}+f^{2}$ all be squares?

Triangles

Pasch's axiom

Let T be a triangle, and X,Y,Z be points on each edge, not at a vertex. The lines XY, YZ, XZ meet the triangle's extended edges at P, Q, R.

How is $\triangle XYZ$ related to $\triangle PQR$?

zeta log function

Namely,

$\prod _{p\in prime}1-\log \left(1-{\frac {1}{p^{s}}}\right)$