magnitude
This is also referred to as the length of v. A vector, represented by a directed line segment 
→ has magnitude equal to the distance between P and Q.
- penta-
- pentagon
- pentagonal number
- pentagram
- per cent
- percentage
- percentage error
- percentile
- perfectly normal
- perfect number
- perfect square
- perigee
- perigon
- perihelion
- perimeter
- period
- periodic point
- peripheral vertex
- permutation
- permutation
- permutation group
- permutation matrix
- perpendicular
- perpendicular axis theorem
- perpendicular bisector