Update Lecture06.md

Lecture06.md

@@ -35,7 +35,11 @@ If you see here, this red line is the ‘number of users’ who have been on you
 
 So what you then do is look for all of your users who have been on your product one day. What percentage of them are monthly active? 100% for the first 30 days obviously, because monthly active, they also end up on one day. But then you look at 31. Every single user on their 31st day after registration, what percentage of them are monthly active? Thirty-second day, thirty-third day, thirty-fourth day. And that allows you, with only 10,000 customers, to get a real idea of what this curve is going to look like for your product. And you’re going to be able to tell, is it asymptotic? It’ll get noisy towards the right side, like I’ m not using real data, but you’ll be able to get a handle on, whether this curve flattens out or does it not. If it doesn’t flatten out, don’t go into growth tactics, don’t do virality, don’t hire a growth hacker. Focus on getting product market fit, because in the end, as Sam said in the beginning of this course: idea, product, team, execution. If you don’t have a great product, there’s no point in executing more on growing it because it won’t grow. Number one problem I’ve seen, inside Facebook for new products, number one problem I’ve seen for startups, is they don’t actually have product market fit, when they think they do.
 
-So the next question that people ask over and over again is, what does good retention look like? Sure! I can have 5% retention, but I’m guessing Facebook had better than that. That’s not going to be a successful business. I get really pissed off when people ask me that question, because I think you can figure it out. I love this story; this is like my one gratuitous story (link on powerpoint) that I’m throwing out here, so the rest of it may not be as gratuitous. But this is a picture that was published in Life Magazine in 1950 of one of the Trinity nuclear bomb tests. There’s a guy named Jeffrey Taylor. He was a British Physicist who ended up winning the Nobel Prize. He was able to figure out, from looking at this picture (picture on powerpoint) what the power of the U.S. atomic bomb was, and Russians were publishing similar pictures, just using dimensional reasoning. Dimensional reasoning was one of the best skills I learned during my time studying physics back in the UK.
+So the next question that people ask over and over again is, what does good retention look like? Sure! I can have 5% retention, but I’m guessing Facebook had better than that. That’s not going to be a successful business. I get really pissed off when people ask me that question, because I think you can figure it out. I love this story; this is like my one gratuitous story (link on powerpoint) that I’m throwing out here, so the rest of it may not be as gratuitous. 
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+But this is a picture that was published in Life Magazine in 1950 of one of the Trinity nuclear bomb tests. There’s a guy named Jeffrey Taylor. He was a British Physicist who ended up winning the Nobel Prize. He was able to figure out, from looking at this picture (picture on powerpoint) what the power of the U.S. atomic bomb was, and Russians were publishing similar pictures, just using dimensional reasoning. Dimensional reasoning was one of the best skills I learned during my time studying physics back in the UK.
 
 What dimensional reasoning is, you look at the dimensions that are involved in a problem, so you want to figure out energy, newtons, meters, newtons as a kilogram, meters seconds to minus two. You want to figure out kilograms, meters squared, seconds to minus two, and then you try to figure out how you can get each of those numbers from what data you have. The mass is the volume of this sphere, so that’s a meter cubed, so you’ve got meters to five over seconds to minus two and he was able to use that to figure out what the power of this atomic bomb was and what the ratios of the power between the Russian and the U.S. atomic bomb was, and essentially reveal one of the top secrets that existed in the world at that time.