Starting calculus at 27 is a viable path for pursuing a career that heavily involves mathematics. While the likelihood of entering pure mathematics research may be lower due to the competitive nature of the field, opportunities in applied mathematics are more accessible. It's important to focus on specific career aspirations for tailored advice. Age should not be a barrier; individuals can learn and progress regardless of when they start. However, it's crucial to recognize that those who have been studying math longer may have an advantage. It is advisable to complete initial coursework before making long-term decisions about a math-focused career, as interests may evolve. Ultimately, dedication and effort can lead to significant improvement in mathematical skills.