__Rational Expression__I want to make 2/3 of a recipe that has fractional measures in it. I know the probability, and I want to figure the odds (or vice versa).

__Root__I am constructing something that needs a square corner. I know the lengths of the sides, and I want to determine the diagonal measure it needs. I know how much prices have increased over a period of years and I want to compute the effective annual rate. I want to know the length of the side of a square that has a particular area.