The rational numbers are the most familiar numbers: 1, -5, ½, and every other value that can be written as a ratio of positive or negative whole numbers. But they can still be hard to work with. The ...

Quadratic fields choose some integer — say, 5 — and include all the numbers of the form a + b 5–√ where a and b are both rational numbers. If the integer in question is positive, then the resulting ...