This may look like a neatly arranged stack of numbers, but it's actually a mathematical treasure trove. Indian mathematicians called it  the Staircase of Mount Meru. In Iran, it's the Khayyam Triangle. And in China, it's Yang Hui's Triangle. To much of the Western world, it's known as Pascal's Triangle after French mathematician Blaise Pascal, which seems a bit unfair since he was clearly late to the party, but he still had a lot to contribute. So what is it about this that has so  intrigued mathematicians the world over? In short,  it's full of patterns and secrets. First and foremost, there's the pattern that generates it. Start with one and imagine invisible zeros on either side of it. Add them together in pairs,  and you'll generate the next row. Now, do that again and again. Keep going and you'll wind up  with something like this, though really Pascal's Triangle  goes on infinitely. Now, each row corresponds to what's called the coefficients of a binomial expansion of the form (x+y)^n, where n is the number of the row, and we start counting from zero. So if you make n=2 and expand it, you get (x^2) + 2xy + (y^2). The coefficients,  or numbers in front of the variables, are the same as the numbers in that row of Pascal's Triangle. You'll see the same thing with n=3, which expands to this. So the triangle is a quick and easy way to look up all of these coefficients. But there's much more. For example, add up  the numbers in each row, and you'll get successive powers of two. Or in a given row, treat each number as part of a decimal expansion. In other words, row two is (1x1) + (2x10) + (1x100). You get 121, which is 11^2. And take a look at what happens when you do the same thing to row six. It adds up to 1,771,561, which is 11^6, and so on. There are also geometric applications. Look at the diagonals. The first two aren't very interesting: all ones, and then the positive integers, also known as natural numbers. But the numbers in the next diagonal are called the triangular numbers because if you take that many dots, you can stack them  into equilateral triangles. The next diagonal  has the tetrahedral numbers because similarly, you can stack that many spheres into tetrahedra. Or how about this: shade in all of the odd numbers. It doesn't look like much when the triangle's small, but if you add thousands of rows, you get a fractal  known as Sierpinski's Triangle. This triangle isn't just  a mathematical work of art. It's also quite useful, especially when it comes  to probability and calculations in the domain of combinatorics. Say you want to have five children, and would like to know the probability of having your dream family  of three girls and two boys. In the binomial expansion, that corresponds  to girl plus boy to the fifth power. So we look at the row five, where the first number  corresponds to five girls, and the last corresponds to five boys. The third number  is what we're looking for. Ten out of the sum  of all the possibilities in the row. so 10/32, or 31.25%. Or, if you're randomly  picking a five-player basketball team out of a group of twelve friends, how many possible groups  of five are there? In combinatoric terms, this problem would be phrased as twelve choose five, and could be calculated with this formula, or you could just look at the sixth  element of row twelve on the triangle and get your answer. The patterns in Pascal's Triangle are a testament to the elegantly  interwoven fabric of mathematics. And it's still revealing fresh secrets to this day. For example, mathematicians recently  discovered a way to expand it to these kinds of polynomials. What might we find next? Well, that's up to you.