"C"
Scales 

C 
The C scale is a fundamental scale, running
from 1 to 10, and is normally located at the bottom of the
slide. Gauge marks are located at C (√(4/π)), ⑫ (dozen), Ⓖ (gross), ρ (π/180), ρ'' (180*60*60)/π), ρ' (180*60)/π), used in radians to degrees conversions, π, τ, C^{1} (√(40/π)), ρ⁰ (180/π) and δ (seconds in a radian in the French decimal system, (200*100*100)/π ). Formula: C = X 
C_{1} 
The C_{1} scale is a ranged
fundamental C scale, ranging from 1 to √10. Gauge mark is present at √10. Formula: C_{1} = √10 × X 
C_{2} 
The C_{2} scale is a ranged
reciprocal fundamental C scale, ranging from √10 to 1. Gauge mark is present at √10. Formula: C_{2} = 1 / ( √10 × X ) 
Celsius 
The Celsius scale is a temperature conversion scale, used with its counterpart, the Fahrenheit scale, to convert between degrees Celsius and degrees Fahrenheit. This scale runs from 23 to 100 °C. 
CF 
The CF scale is a folded C scale, with the
fold (or wrap) occurring at π (3.14). This scale
expedites the multiplication of values by π. Gauge marks are located at π and τ. Formula: CF = π × X 
CF/m 
The CF/m scale is another folded C scale, but
this time, the fold is at 2.3 (natural log of 10).
This scale is useful when converting results between base 10
and base e. Gauge marks are located at π and τ. Formula: CF/m = ( log_{e} 10 ) × X 
Ch 
The Ch scale is a hyperbolic cosine scale,
ranging in value from 0.0 to 3.0 Formula: Ch = cosh X 
CI 
The CI scale is an inverse C scale, reversed
in direction from the C scale (reciprocal scale). Gauge marks are located at π and τ. Formula: CI = 1 / X 
CIF 
The CIF scale is a reciprocal folded C scale,
folded at π like the CF scale, but reversed as well, like
the CI scale. Gauge marks are located at π and τ. Formula: CIF = 1 / ( π × X ) 
Const 
The Const scale has several physical
constants represented whose values can be read from the D
scale. The Const scale may only be present on the top
or bottom rule. 