<p>At least in the US universities, it is probably not that difficult to study both, particularly if you are so advanced in math that you will skip many of the frosh/soph level courses.</p>
<p>Of course, if you want to become a mathematician or biologist, you need to choose when you apply for PhD programs.</p>
<p>However, note that, in the US, math majors do have somewhat better job and career prospects than biology majors, since many adapt well enough to finance and computers (of course, a few electives in those areas can help). See the <a href=“http://talk.collegeconfidential.com/internships-careers-employment/1121619-university-graduate-career-surveys-5.html#post16559971[/url]”>http://talk.collegeconfidential.com/internships-careers-employment/1121619-university-graduate-career-surveys-5.html#post16559971</a> .</p>