What is a common feature of ADHD as identified in clinical signs?

A short attention span is a hallmark characteristic of Attention-Deficit/Hyperactivity Disorder (ADHD) that is consistently identified in clinical settings. Individuals with ADHD often struggle to maintain focus on tasks or activities, particularly if they are perceived as boring or repetitive. This difficulty can manifest in various contexts, such as in academic environments where sustained attention is necessary for learning and completing assignments.

While the other choices relate to challenges that may be experienced by individuals with ADHD, they are not universally recognized features of the disorder. For example, difficulty with multi-digit numbers and problems with handwriting may occur due to learning disabilities or other factors, but they do not specifically define ADHD. Similarly, the inability to recognize operator signs is more related to specific learning difficulties rather than a core symptom of ADHD. Therefore, the short attention span stands out as a defining trait most commonly associated with ADHD, reflecting the core nature of attentional issues in this condition.