A mixed fraction is an improper fraction written in the form . In common usage such as cooking recipes, is often written as (e.g., 1 ), much to the chagrin of mathematicians, to whom means , which is quite a different beast from .
(The author of this work discovered this fact early in his mathematical career after having points marked off a calculus exam for using the recipe-like notation. Future mathematicians are therefore encouraged to avoid mixed fractions, except perhaps in the kitchen.)