Interior Algebra is a branch of mathematics that helps us to understand how numbers work. In interior algebra, we use equations (sentences with numbers in them) to figure out what the answer to a problem might be. For example, if I have the equation 2 + 5 = 7, I can figure out that when I add 2 and 5, the answer I get is 7. Interior algebra is a big part of many different branches of mathematics, like geometry and calculus.