Quartile Variation Coefficient
where
and 
are the first and third Quartiles and 
is the InterquartileRange.- Trilinear Coordinates
- Trilinear Line
- Trilinear Polar
- Trillion
- Trimagic Square
- Trimean
- Trimorphic Number
- Trinoid
- Trinomial
- Trinomial Identity
- Trinomial Triangle
- Triomino
- Triple
- Triple-Free Set
- Triple Jacobi Product
- Triple Point
- Triple Scalar Product
- Triplet
- Trip-Let
- Triple Vector Product
- Triplicate-Ratio Circle
- Trisected Perimeter Point
- Trisection
- Trisectrix
- Trisectrix of Catalan