It was four years ago when I discovered Khan Academy, which as far as I can remember a Youtube channel with more than a thousand videos. If I am not mistaken, it was only then managed by Salman Khan, it’s founder.
A year ago or two, when I searched the internet, I learned that Khan Academy has already its own website and it is run already by a group of educators. Three weeks ago, I started using the website. As of this writing, I have already watched 29 videos (oh yes, I watched them from start to end) and earned 56,340 points. 🙂 » Read more
We have had several discussions about the factorial notation, so I think this introduction is a bit late. However, it is important that you know these basic facts in order to perform calculations and understand better in later discussions.
The factorial of a non-negative integer is the product of all the positive numbers less than . For example, the
In Introduction to Permutations, we have discussed that there are ways to arrange distinct objects into a sequence. For instance, if we have 3 objects namely A, B, and C, then they can be arranged in ways. The arrangement are as follows:
We have also learned some reasons why mathematicians chose the definition . » Read more