Determinant

A determinant is like a number that you can calculate from a square grid of numbers. It tells you different things about the grid, and is used in lots of different areas of math. To calculate the determinant you start by writing the numbers from the grid in a neat table, and then multiply the numbers from the top-left corner to the bottom-right corner, and then subtract the numbers from the top-right corner to the bottom-left corner. That's the determinant!