The MathQuill editor appears to have trouble resolving factorials in the denominator of a fraction. For example, entering 3!/(2! 4!) in the editor correctly displays as \frac{3!}{(2! 4!)} (and problem evaluation correctly evaluates it as the intended fraction 3!/(2! 4!)), but removing the parentheses in the denominator results in the MathQuill display showing \frac{3!}{2! 4!}, but preview and grading both interpret the input as \frac{3!}{2!} (4!).