Per 
Class: Safe
Containment Procedures: Keep in locked metal vault with warning label on the outside.
Description: SCP-4991 appears as an ordinary French-suited playing card (the King of Spades), with each instance of the "spade" having been replaced with a 4 in the Times New Roman font, point 26.
The act of holding SCP-4991 causes increasingly worse function of the posterior parietal cortex, ventrotemporal occipital cortex, and the prefrontal cortex, causing the owner of SCP-4991 to become increasingly bad at math in particular as well as other functions linked to these areas. Testing confirms these effects only extend to humans.
SCP-4991 appears to have come into existence spontaneously; it was found mixed into a pack of playing cards at ⬛⬛⬛⬛⬛⬛⬛ Casino, Las Vegas, in 20⬛⬛ by Agent B. ⬛⬛⬛⬛. SCP-4991 was first noticed when the aforementioned Agent noticed the card's unusual print, and the fact that the player holding it insisted fiercely that his high card was a three-of-a-kind.
