Final answer:
Mujdat's excessive fear is categorized as an obsession, and his repeated checking behavior is a compulsion, both of which are indicative of Obsessive-Compulsive Disorder (OCD).
Step-by-step explanation:
Mujdat's excessive fear of making mistakes is an obsession, and his behavior of checking calculations hundreds of times is a compulsion. These terms are central to the diagnosis of Obsessive-Compulsive Disorder (OCD), which is characterized by the presence of obsessions, which are recurrent and persistent thoughts, and compulsions, which are repetitive behaviors that the individual feels driven to perform in response to an obsession. The irrational fear of making a mistake leads to an obsessive thought pattern, while repeated checking is the compulsive act aimed at mitigating perceived risk or preventing the obsession from becoming a reality.