A number of students outside of the typical Finance & Accounting degrees will face the same question from a resume reviewer: do you have the quant skills needed to succeed as a consultant? Read through to learn a little bit more about what you need to do to prove your math smarts.
First things first - if you're applying for internships, then you still have time for this - make sure that you take quantitative courses! This can be Finance, Accounting, Economics, Stats, etc. If a liberal arts student can pull off an A in differential calculus, then an interviewer will take your application seriously.
While getting an A in a qualitative course can be very challenging (and in fact at McGill, our Organizational Behaviour courses had the lowest % of A's of all disciplines in the university) you need to prove that you're comfortable crunching numbers.
If it's too late for that, then you have a couple of options:
1. If you did well on the SAT in the math section, then put that down. As an added bonus, SAT Math scores have been positively correlated with success as a consultant.
2. If you're willing to take the GMAT (More about that in the '6 Steps to Success', available to all registered users) then a strong math score will really help your application. Plus, you can re-take the GMAT as many times as you want and your scores are valid for 5 years.
3. Emphasize quantitative aspects of roles or jobs that you've held - balancing budgets, heavy excel, etc.
4. This is more of a personal preference - while I generally recommend against putting "relevant coursework" on your CV (unless it's really impressive stuff), if you're a liberal arts student who has taken a few quant courses, then it's worth putting that down - it shows that you recognize (and are addressing) the perceived weakness.
5. Practice your math! You will absolutely be tested on it come interview time. Work on market sizings, practice your guesstimation, and focus on cases with a quantitative component. This will work hugely to your advantage; as Victor Cheng of www.caseinterview.com puts it - "McKinsey likes to hire engineers with people skills and poets who can do math".