The Pi-Lingual t-shirt features geometric diagrams for area and circumference of a circle, and a wide variety of advanced formulae featuring Pi.
T-shirt is Black.

Pricing: $17 to $19.

Front: "It can be radical, irrational, too complex to be real" (The quadratic formula)...
Back: "But it gets to the root of the problem."
Available in Black, Ash Gray, and White.

Pricing: $14 to $16.

The quadratic formula with a diagram of a completed square, and the phrase "Solutions for the completely square."
Available in Black, Ash Gray.

Pricing: $17 to $19.

For those who make algebra too complicated.
Small Print: "y'gotta parabolam?" And "y? =because it's there."
T-shirt is Ash Gray.

Pricing: $17 to $21.

Front: "Properties of Math Dept."
Back: "Properties of Math Department", followed by various additive and muliplicative properties.
Available in Navy Blue, Indigo Blue, and Violet.

Pricing: $17 to $21.

Features a valentine heart as the argument for functions from algebra, trigonometry differential and integral calculus, and linear algebra, with the caption "My normal approach is useless here".
This design is printed on a somewhat lighter weight shirt than our usual heavyweight t-shirts.
T-shirt is Black.

Price: $18.