You should know this number theory result -- Bertrand's Postulate
12:13
Always even.
18:47
a nice floor problem from the IMO long list.
19:48
AN ELEMENTARY PROOF OF BERTRAND'S POSTULATE! Special #SoMe1
20:21
The Freshman's Dream (a classic mistake) - Numberphile
19:59
You should know this abstract algebra exercise
11:04
A nice number theory problem from an Argentinian math olympiad
17:21
an interesting result regarding Pythagorean triples...
15:21