Some of the entries above need some elaboration. For example, a problem was considered a trigonometry problem if a trigonometric function is used in the statement of the problem. Many of the geometry problems have solutions, in some cases alternative solutions, which use trigonometric functions or identities, like the Law of Sines or the Law of Cosines. These problems are not counted as trig problems. A very small number of problems are counted twice in the table.
Many problems overlap two or more areas.
For example, a problem might ask how many of certain geometric configurations are there in the plane. Such a problem could be counted in any of the three categories geometry, combinatorics, or absolute value, floor and ceiling. In cases like this, we looked closely at the solution to see if it was predominantly of one of the competing types. This situation often arises in the case of number theory-combinatorics problems because many of these types of objects that we want to count are defined by divisibility or digital properties encountered in number theory, but often invoke binomial coefficients to count. Many of the early problems are what we might call exercises.