The phrase "didst a number" is an archaic and outdated way of saying "performed an action" or "completed a task." There are many synonyms for this phrase that are more commonly used in modern English, such as "accomplished," "executed," "acted upon," "carried out," "undertook," and "finished." These words convey a sense of action and completion, indicating that a task has been successfully accomplished. Using more contemporary language can help improve the clarity and impact of your writing, making it more accessible and engaging to modern audiences.