Klarner's Theorem
An 
Rectangle can be packed with 
strips Iff 
or 
.
References
Honsberger, R. Mathematical Gems II. Washington, DC: Math. Assoc. Amer., p. 88, 1976.
- Regular Polygon
- Regular Polyhedron
- Regular Prime
- Regular Ring
- Regular Sequence
- Regular Singularity
- Regular Singular Point
- Regular Surface
- Regular Triangle Center
- Regulus
- Reidemeister Moves
- Reidemeister's Theorem
- Reinhardt Domain
- Relation
- Relative Error
- Relative Extremum
- Relatively Prime
- Relative Maximum
- Relative Minimum
- Relaxation Methods
- Remainder
- Remainder Theorem
- Rembs' Surfaces
- Removable Crossing
- Removable Singularity