The first digit is ...

graeme · 2003-09-02, 08:40

Ok - I'm not sure if this is a "puzzle" or a general knowlege or just a curiosity, but here goes.

Measure the length of a river, what's the most likely value of the leading digit of that length?

Harder (not impossible): Why?

xilman · 2003-09-02, 08:55

Quote:

Originally Posted by graeme

Ok - I'm not sure if this is a "puzzle" or a general knowlege or just a curiosity, but here goes.

Measure the length of a river, what's the most likely value of the leading digit of that length?

Harder (not impossible): Why?

Hmm, it's difficult to respond to this one without giving away the solution, so I'll give a pointer to the solution. Look in Knuth Section 4.2.4.

As should be clear from my answer, it should be general knowledge to anyone with an interest in computer science.

Paul

graeme · 2003-09-02, 09:58

Well we learn something new every day. I had no idea this was in Knuth.

I've come across it through several different means, with various explanations.

roy1942 · 2003-09-02, 14:06

If you are old enough to own a slide rule, a glance shows that about 30% of the real estate on the scale is taken up by numbers starting with this same digit. Same reason.

Gary Edstrom · 2003-09-02, 16:35

Quote:

Originally Posted by roy1942

If you are old enough to own a slide rule, a glance shows that about 30% of the real estate on the scale is taken up by numbers starting with this same digit. Same reason.

Not to get off on a tangent, but "You know you are getting old when you mention a slide rule to a fellow engineer and he has no idea what you are talking about." I had to bring my old slide rule in to show him. He had never seen one before.

xilman · 2003-09-02, 16:49

Quote:

Originally Posted by Gary Edstrom

Not to get off on a tangent, but "You know you are getting old when you mention a slide rule to a fellow engineer and he has no idea what you are talking about." I had to bring my old slide rule in to show him. He had never seen one before.

My first slide rule had the S, T and ST scales so that I could go off on a tangent. Some of the others in my collection are not so well endowed.

<sigh>
Now everyone will join in, each in his own key of course, until the forum is just soggy with nostalgia.
</sigh>

Paul

Orgasmic Troll · 2003-09-03, 02:18

not to weight in with nostalgia, but I'm 23, and I know what a slide rule is .. but I might need to get out more..

Fusion_power · 2003-09-03, 04:27

Travis,

Knowing what it is is not the same thing as knowing how to use it.

My first encounter with a slide rule was in "Have Space Suit Will Travel". by Robert Heinlein.

To return to topic, the one thing you can say is that the number in question is unique.

I once heard about a group of four mathematicians who decided to write a book on the properties of the number 1. Four books later they decided to give it up.

Fusion

2003-09-02, 08:40	#1
graeme Jul 2003 41₁₀ Posts	The first digit is ... Ok - I'm not sure if this is a "puzzle" or a general knowlege or just a curiosity, but here goes. Measure the length of a river, what's the most likely value of the leading digit of that length? Harder (not impossible): Why?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Digit sum of p of Mp is never 6 or 9?	noemata	Lounge	3	2016-01-22 10:12
Factoring a 160 digit RSA key	swistak	Factoring	6	2010-11-17 23:49
How much digit in the M?	Lorenzo	Math	17	2010-08-26 16:54
160 digit factor found of 366 digit (PRP-1)	AntonVrba	Factoring	7	2005-12-06 22:02
10 digit prime in e	TTn	15k Search	15	2004-10-18 03:11

2003-09-02, 09:58	#3
graeme Jul 2003 101001₂ Posts	Well we learn something new every day. I had no idea this was in Knuth. I've come across it through several different means, with various explanations.

2003-09-02, 14:06	#4
roy1942 Aug 2002 101111₂ Posts	If you are old enough to own a slide rule, a glance shows that about 30% of the real estate on the scale is taken up by numbers starting with this same digit. Same reason.

2003-09-03, 02:18	#7
Orgasmic Troll Cranksta Rap Ayatollah Jul 2003 641 Posts	not to weight in with nostalgia, but I'm 23, and I know what a slide rule is .. but I might need to get out more..

2003-09-03, 04:27	#8
Fusion_power Aug 2003 Snicker, AL 7×137 Posts	Travis, Knowing what it is is not the same thing as knowing how to use it. My first encounter with a slide rule was in "Have Space Suit Will Travel". by Robert Heinlein. To return to topic, the one thing you can say is that the number in question is unique. I once heard about a group of four mathematicians who decided to write a book on the properties of the number 1. Four books later they decided to give it up. Fusion