If you have a great grasp of mathematics, it is quite indicative that you will probably fare well in your professional life as well. This skill does certainly give you an edge on others in job interviews but only when combined with a thorough statistical knowledge.
It is a great skill to be able to compute mathematically. However, if one does not have statistical skills to back up his mathematical knowledge, it will not make a successful career. Therefore, a thorough grounding in statistics is the order of the day. Companies are not looking for someone who can solve calculus problems but for an employee who can make a difference to the company with the relevant statistical data.
Professional achievements and a company's success are generally measured in statistical terms. Furthermore, a country's economic progress is also measured in the same way! Company YXZ topped sales in the FMCG sector with a whopping 25% margin - how would you interpret that if you had no sound statistical knowledge? Most jobs require you to effectively demonstrate the results and trends from a given set of numbers using spreadsheet programs in a visually effective way. Therefore, it is wise to go through statistics textbooks, whether borrowed or bought, to gain a fair grounding on the concept before being an undergraduate.
So if you want to be abreast of statistical knowledge and skills and do not intend to get a degree in the subject, then go ahead and buy a book that will provide you the necessary information. Education is an important investment that everyone should make, and today, it has become a very expensive proposition keeping in mind the soaring tuition fees, lodging, food, and books. Books are certainly expensive and can hurt you financially if you are lying on a low budget; therefore, you should be judicious by investing in used/secondhand statistics textbooks, which will cost half the price of a new book. These can be bought from various college bookstores and online retailers that offer books on a wide range of subjects.
Taking into account the ubiquitous nature of statistical knowledge in the modern-day world, it is pertinent to at least go through one textbook before the completion of under-graduation! Statistical data is everywhere; you can encounter it in the newspapers, in magazines, on TV - everything is measured in terms of percentages, ratios, diagrams, graphs. Each piece of vital information is supported by statistical facts and figures, so it will not be a good thing to remain ignorant about the statistics.