SCP-033 is an entry on the SCP Foundation Wiki which describes an as-of-yet unknown integer that is described by a set of mathematical equations ranging from the mediocre to the fiendishly abstruse, and which was designated by the fictitious Professor Hutchinson as \(\Theta '\). It is a number that cannot remain fixed in our reality, and seeks to 'fade away' from any surface upon the description of it is written. It is approximately between █ and █, according to the Wiki.

The number is fictitious of course, but it provides insight as to how mathematicians might have felt about the introduction of the imaginary value \(i\) within mathematics, which is a number that likewise cannot be said to truly "exist" in our reality, (in the sense a representation of it cannot be produced, unlike how the naturals may be symbolized by a grouping of various objects), but has a firm hold on the calculation of very real and tangible matters, such as the trajectory of a cannon ball.