**00:00:01** – this is lesson #13 and I'm gonna show you more javascript using the Collatz conjecture,**00:00:05** – this is what we got, a textbox with a number and a button and when you click this button**00:00:11** – you get a series of numbers that seem pretty unpredictable, you can feed it any number**00:00:15** – – Collatz was a German mathematician who stumbled upon a very simple algorithm that turned out**00:00:22** – to be an extremely hard mathematical problem, I suggest you not to try to solve it, it says**00:00:27** – that you take a positive integer and if it's even you divide it by 2 and if it's odd you**00:00:33** – multiply it by 3 and add 1 and the conjecture says that you will eventually reach 1 in every**00:00:40** – case, this has not been proven yet – so when you click the button, we will call this function**00:00:46** – and first of all we clear the output for which we use the div here, then we take the value**00:00:53** – of the textbox and put it into variable n then we use a conditional statement which**00:01:01** – is very useful in programming, we say that if the value of n is less than 1 then we replace**00:01:07** – it with something else, here we make sure that the number that we feed into the algorithm**00:01:12** – is bigger than 1 or equal then we print it and then we have a cycle here – we check if**00:01:22** – the number is even by dividing it by 2 and check if its modulus is equal to zero because**00:01:29** – if so then it can be divided by 2, then we replace its value with something – we have**00:01:37** – another conditional branch here with a keyword else which says that if it's not even then**00:01:45** – we replace its value with something else which is 3 times n plus 1 then we print it – if**00:01:51** – the condition is not met then the cycle exits and continues interpretation – our program**00:01:59** – will end here because we don't have any more commands here so feel free to play with it,**00:02:04** – thanks for watching

Video Url:

http://youtu.be/EHQ1vxOvOrg