The Big X and Multiplication - Numberphile
9:20
Pentominoes and other Polyominoes - Numberphile
10:33
Caboose Numbers - Numberphile
27:29
What Is The Most Complicated Lock Pattern?
13:01
The Change from Roman Numerals - Numberphile
26:51
New divisibility rule! (30,000 of them)
11:16
The Game You Can't Win
33:06
Something Strange Happens When You Keep Squaring
17:05