
Also TryPapers
 Mathematical Constants (Wikipedia.org)
Includes Brun's constant, Catalan's constant, Champernowne constant, De BruijnNewman constant, EmbreeTrefethen constant, ErdösBorwein constant, EulerMascheroni constant, Feigenbaum constant, Golden ratio, Khinchin's constant, Landau's constants, LandauRamanujan constant, Lévy's constant, Mathematical constant, MeisselMertens constant, Omega constant, Pi, RamanujanSoldner constant, Square root of two, and Viswanath's constant.
 Dimensionless Number (Wikipedia.org)
"In the physical sciences, dimensionless number is a quantity which describes a certain physical system and which is a pure number without any physical units. Such a number is typically defined as a product or ratio of quantities which do have units, in such a way that all units cancel."
 Measurement (Wikipedia.org)
Provides articles on measurement by topic.
 Scales (Wikipedia.org)
Includes Bark scale, Beaufort scale, Fujita scale, Glasgow Coma Scale, Kardashev scale, Logarithmic scale, Mel scale, Mercalli Intensity Scale, Musical Scales, Palermo Technical Impact Hazard Scale, Pediatric Glasgow Coma Scale, Richter magnitude scale, SaffirSimpson Hurricane Scale, Scoville scale, Tanner stages, Time scale, Torino scale, and Volcanic Explosivity Index.
 Tuning (Wikipedia.org)
Includes Beat, Blue note, BohlenPierce scale, Equal temperament, Fundamental frequency, Harmonic series (music), Just intonation, Just tuning, Mathematics of musical scales, Meantone temperament, Microtonal music, Musical tuning, Node (physics), Overtone, Pseudooctave, Pythagorean tuning, Regular temperament, Spectrum, Timbre, Tuning, Well temperament, and Xenharmonic
 Unusual Units of Measurement (Wikipedia.org)
Provides articles on measurement by topic.
 Vedic Timekeeping (Wikipedia.org)
Provides the Hindu metrics of time.
 Weights and Measures (Wikipedia.org)
Provides articles on weights measurement.
