Math is not a prerequisite of studying the law. However, to be a successful lawyer, you likely will need to need to understand certain aspects of math to best support your clients. Having a basic understanding of how math is used in finance and basic statistics is probably enough in most cases though depending on the type of law you practice, it could be much more extensive.
A lawyer with a thorough grounding in science, mathematics and business will be better equipped to serve clients.
Math skills are necessary to plan your business operations, to decide how much to pay your staff, how much to charge clients in order to pay your bills, taxes, rent, utilities, and other business expenses. You’ll need good math skills to analyze evidence, to negotiate business deals, to write meaningful contracts, and to interpret law.
Either that, or plan on paying half of your salary to accounting firms to do all the math for you- and accountants are expensive.