numerical challenge

5 divides every fifth number. 4089/5 = 817 + 4/5 Anoher 5 divides every 25-th number. 4089/25 = 163 + 14/25 Yet another 5 divides every 125-th number. 4089/125 = 32 + 89/125 etc.

Number of zero's = [4089/5] + [4089//25] + [4089/125] + [4089/625] + [4089//3125] = 817 + 163 + 32 + 6 + 1 = 1019.

Sylvia Else schrieb:

Hello,

I think there is a typing error in this line: a) is 56 * 171 * 170^2 it should be a) is 86 * 171 * 170^2.

172/2 is 86 not 56

But this error does not influence the result because the 5 or 8 is dropped anyway.

But I love this very clever calculation.

Bye

Or MATLAB:-

ans =

1189408362050899232331742548544079352843642973887737980381143384247782716222833932275790528049591602801982365577332286115374553061109422815431261462944420553436302158846639937649074486702295858231061014815003701856067898072301499489535982821308553995236716650994484275639670292828652624433814244134653337397556701859802285204337784880847597171549786961194804353449316566215601255402641.

Best regards, Spehro Pefhany

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Sadly, my typing is more accurate than my calculating, so it's probably the latter that went astray. Well spotted.

Sylvia.

With that answer? Are you sure? ;-)

Been there. It's taken some convincing, at times, to get management to understand that sometimes more people = less work. It's often too late to improve a schedule, by *any* means.

452? A zero for every 10 (408), another for every 100 (in addition to the one for the 10th 10) (+40), and another for every 1000 (+4).

Unlike many posters here, I typically trim my posts. But this one is so classic that I want to include all of the context.

This is so clearly an issue of miscomunication that even I can spot it. Yet no one is willing to go the extra mile and explain clearly enough where the confusion is. Rather this collection of alleged professionals prefer to begin name calling and abusing each other.

Larkin's post with the 0.6 Volt answer was saying this was an answer that an applicant gave. I can see where this was misinterpreted as "one valid answer" rather than "one applicant's answer". The rest of the conversation really didn't explain any more clearly and was also misinterpreted. Given the obvious context I can see why the following comments were also misinterpreted.

Can't any of you act like adults?

They say that things are often said on the Internet that would not be said if you were face to face. I wish there was a way to change that.

Rick

Even if the applicant couldn't solve this problem (even at home) because he just wasn't well enough versed in the math or just didn't think of the solution, that doesn't mean he can think in other terms nor does it mean he wouldn't be good at problem solving directly related to the job.

I don't see this as a good interview question. But then I didn't get the answer... but I did learn from it.

Rick

True.

s

2. >

mod

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the

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here

the one

How many terminal zeros do you think 5! has? (No fair calculating 5!, just use the same reasoning you used for 4089!.)

one

I originally discounted 2s and 5s because the only 9*0 ends in zero (assumed that the '9' made a difference - it doesn't). Obviously, there is also 2 times 5 in each decade, so there are 408 (x0) + 40 (x100) +4 (x1000) + 409 (2x5) = 861.

snipped-for-privacy@att.bizzzzzzzzzzzz wrote: ) I originally discounted 2s and 5s because the only 9*0 ends in zero (assumed ) that the '9' made a difference - it doesn't). Obviously, there is also 2 ) times 5 in each decade, so there are 408 (x0) + 40 (x100) +4 (x1000) + 409 ) (2x5) = 861.

I have no idea what you mean with 9*0 and why they should make a difference.

Also, you still made a mistake, 861 is not the right answer.

SaSW, Willem

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John Larkin wrote: ...

Germanium or silicon? PNP or NPN? ;)

Roberto Waltman [Running for cover...]

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For a (slightly) more advanced test..

I cheated and googled. Here is an easy general method, particularly easy with a pocket calculator:-

and I also get the correct answer from MATLAB by using: vpa('4089!',50000)

Then copy/paste the zeros into Ultraedit and looking at the column number of the last zero. xxx9.

Now we are getting somewhere. Also need to know the Hfe to answer the Ib and Ie parts.

Might also be good to know the temperature and the transistor part number.

LOL

Good one Spehro. Better hope that B-E zener doesn't fire.

It's impressive how many people don't understand emitter followers. Like, I saw one audio amp that had a 2N3055 emitter-follower output, a huge coupling cap to the speaker... and a 1K emitter pulldown resistor.

But, to clarify, one job applicant actually said that the base voltage was 0.6. I guess he felt that all base voltages are 0.6. One other guy said that the collector voltage was 0.2, because the transistor is saturated.

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Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
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VME thermocouple, LVDT, synchro   acquisition and simulation

You might actually need to run for cover...

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation