° (degree sign)
Converts degrees to radians.
Syntax

x°

x
is a real or complex number

Description
This is a postfix operator that performs the mapping x ↦ x⋅π/180
, thus converting its operand from degrees to radians.
Examples
sin(90°)
1
120° + 60°
3.14159265359 (=π)
∫(sin(x), x, 0°, 180°)
1.99999999984