How necessary is Math senior year for college admissions??

@gumbymom:

When a college suggests 4 years of math in high school, what are the considerations that go into that, do you think?

Is that a consideration leaning toward actually sitting in a math class for four years during the high school career, or of completing APCalc BC ( the highest level of math at the high school for those on a true math course; earned a 5 )?

If one completes AP Calculus BC in junior year, and opts to self-study an AP science course (Chem, not offered at school), instead of taking the high school’s AP Stats course (the only math course left), is this a terrible thing to do from an admissions perspective?