imaginary i, comma - spherical coordinates: first coordinate gives magnitude (complex modulus/radius) of the number, the second number gives the angle from the positive real axis measured counterclockwise toward the 'positive' imaginary axis (default: in the primary branch/Arg) as measured in some units (which that number should contain; the contextless default will suppose radians); the angle is not normalized.
Digit/number: pi (denoted "π"; approximately 3.1416...); the constant defined by the ratio of the circumference to the diameter of all circles in Euclidean space.
digit/number: ideal first Skewe's constant Sk1 ; the first (minimal positive) infimum for which all greater x in some neighborhood have the property that it is false that the prime counting function at x is less than the logarithmic integral function at x
digit/number: tau (denoted "τ": approximately 6.2831...). The constant defined by the ratio of the circumference to the radius of all circles (default: in Euclidean geometry).