I love the comparison, but I would imagine that due to mobile phones and contact lists, it's quite possible to be in love without knowing any phone numbers.

Personally I know the numbers of the (at a guess) 20 people I call most often, but I always assumed that, in 2011, I'm the exception not the rule.

Not particularly relevant, his point stands either way, just interested to know if other people on HN still find themselves memorising phone numbers.

The only numbers I know are the ones that haven't changed since before I was a teenager (basically just my parents' numbers and 911), my own Google Voice number, and Bing 411. That's partially because I can always look up numbers in my contacts, on Facebook, or online, and partially because I make phone calls less than once a week.

I don't bother remembering a phone number, unless calling that number will result in the person on the other end bailing me out of jail.

So far, 100% success rate.

wrt being bailed out of jail?

in 2011 we do not know phone numbers anymore, but those braincells now store passwords.

I don't directly remember any new numbers, but I know how the DTMF sequence for the number is supposed to sound when dialed. I could always work back from that to get a human-readable phone number if I needed it.

Like Jebdm, the only numbers I really know are those that haven't changed in a few decades and my own cell number. But I also prefer face to face conversation over telephone, so I'm only likely to call you if I can't find you. (And then I'm more likely to just text or e-mail....)

Are you joking or did you used to be a phreaker? That is hardcore! +1

No joke, though I'm not an old phone phreak (sorta...). It's just like remembering music - every number sings its own 10 note song.

At least it was until my cellphone stopped playing back DTMFs for stored numbers. SIP and quiet dialing have almost killed the music.

I got a new phone number three weeks ago and I still haven't memorized my own phone number.

Use address then.

Ironically the opposite for me. I can tell you my father's mobile and home numbers, but not his address (I know the post code but not the flat number...), despite visiting him 2-3 times a month.

I can also tell you my grandmother's number, but not her address. Again, I'll visit her maybe twice as often as I'll call her (not that many times in a year, she lives 60 miles ago).

I'm a landmark person. I don't know the address of where I work, I just know what the places I need to turn at look like.

When I was in graduate school taking my qualifying examination, I stood in front of my 5 advisors answering their questions one by one about my dissertation project (pre-defense). The first time I failed. They questioned me for 2 hours on every detail of my project and grew impatient every time I gave them a hand-wavy answer. The second time I passed. The questioning lasted 15 minutes. I had spent the previous 3 months since the first failure reading every single book on my domain atleast twice. I was also angered (as were they) the first time when they asked simple questions and the answer just didn't bubble to the top of my memory. I think the second time around, they were almost freaked out by my eagerness.

Perhaps an undervalued skill is determining the amount of accuracy necessary? When asked on the spot like that, you may be better off giving an education guess than shuffling through a giant binder.

Sometimes I'll see somebody being asked a question which I know they know the answer to but they'll misinterpret the motivation behind it and the desired answer. This makes me wonder, is it a situational thing or some kind of cultural/language barrier?

I also notice that solid hackers get along really well together because they can anticipate how the other person thinks and know what they want to know (or already know/don't care about). Hacker types seem to be much more culture-biased than the average person, so when you introduce somebody from the other end of the spectrum you get a huge rift.

I suppose that 10 minutes is enough time to notice if this rift exists.

I'm totally like that. Many times people will ask me questions (oddly, this only happens in interview-type situations) when I will just entirely space out on the motivation. I just can't understand what they want and the question either seems too vague or too obvious. I don't know if it's me or them, but it happens.

I find this statement at odds with this one:

The very best startup ideas, the ones that are the biggest successes, tend to be the ideas that you don't know are even going to work.

Knowing a domain and being able to predict success in it are two very different things.

EDIT: A better example. Before Ford released the F-150, it seemed to be a solution in search of a problem. It was somewhere between the F-100 and F-250 and none of the pre-market reviewers really seemed to like it. Ford released it anyway. The F-150 went on to become the most popular variant of the best selling truck series for 34 years.

That's an interesting example, but it's not from a startup. Ignoring that, it could still hardly be considered an idea Ford wouldn't know if it would work at all, because they already had success with similar ideas.

It's not from a startup but there's an interesting parallel. It's as if Ford had a $10/month plan and a $25/month plan. They didn't see a need for a $15/month plan but they created one anyways and it took off.

The thinking behind its success is likely similar: the highest tier of service often acts as a decoy for the one you really want them to pick... the second highest plan. It gives customers a reason to reject the "luxury" option and settle instead for the middle of the pack option which is only slightly more expensive than the cheap option, allowing them to feel like they made the sensible choice.

And how do you relate this back to the biggest startup successes like google or facebook?

I'm not sure it directly relates as Google and Facebook don't generally have the "choose from the following plans" kind of revenue model.

How do you prepare for this? How do you practice answering these questions? I feel like I can never know enough about the business.

So I would ask, for any of you who have pitched to investors / YC, how do you go about preparing and practicing?

Same way the best engineers "prepare" for a job interview - by largely ignoring it. Instead of studying Java certification books they hack in Python, C, and Haskell and read about interesting algorithms in their spare time. When it's time for a job interview, all they have to do is show up.

If you talk to one of your target customers and one startup founder in a similar field a day, in three months you will have spoken to ~180 people that are intimately related to your business. You'll know more about your domain than you ever wanted to, and when the YC interview comes, there is nothing to prepare for.

That's the whole point it's not about "preparing and practicing" for the pitch/investors. You'll never "know enough". Instead if you're passionate about the domain and somewhat intelligent then you should know everything the investors know and a hell of a lot more. The investors should have a fraction of the knowledge and experience that you have and thus should be practically incapable of asking you a question you don't know the answer to.

If you can't answer the question then you're either not particularly passionate, or you're not very smart - either way you're not worth investing in.

I don't know if that's true. Some ideas anyone can have a cursory knowledge of your domain, and can identify corner cases you may not have considered. That's mostly the stuff I'm concerned about. I'm curious what kind of corner cases people can ask questions about.

Then you tell them you don't know and you walk them through an educated guess. They just want to know that you understand your supposed area of expertise.

(full disclosure: haven't pitched to investors/YC)

Just talking about your product with colleagues, mentors, friends, etc. can help you get prepared. Most likely they will ask you questions and it can be like a mock "interview".

Like most one liners, that's not very fair. I don't even know my own phone number. Why would I? I consider it bad interface that I have to ever even hear this kind of technical detail at all. I know my number and every other number by the name of the person or place I want to call.

Likewise, are you sure the people are looking in their document because they don't know? Maybe they answered this question at some previous time in a really concise and elegant way and want to reuse it? Maybe they have a page in their that visually illustrates the answer?