Being an engineer, I generally use numerical values for any and all numbers, irrespective of the 'size', based on the idea that this approach is less ambiguous than writing them out as text.  However, my wife, professionally trained as an executive secretary, says that if the number is 10 or less, that you spell it out (I've never asked her about the parenthetical issue but I suspect that from her point of view, it would be unnecessary if you had followed the 'rules' to start with).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
UG/NX Museum:   http://www.plmworld.org/p/cm/ld/fid=209

To an Engineer, the glass is twice as big as it needs to be.
 

I was taught as Baker's wife says!!

Same here, but then I was also taught to put two spaces between sentences!

"Good to know you got shoes to wear when you find the floor." - Robert Hunter
 

I was taught that for clarity that all numbers should be in numeral form, not in word form, for any structural engineering use. I guess my engineering mentors thought that their clients, contractors, plan reviewers, etc. could not read well enough to understand the word form of numbers.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

I see parenthetical numbers used a lot in pseudo legal documents & similar.  I always take it to be an a$$ covering exercise.

Here a question, if you use numbers in parentheses do you need to add a disclaimer at the end of the letter/report/etc. stating that any discrepancy found between the numeral form and the word form that the greater requirement shall govern?

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

The numbers in parenthesis thing does three (3) things:  one (1) it makes the document much more difficult to read; two (2) it makes the reader wonder why the writer felt it was necessary to unnecessarily clutter the document with parenthetical numbers such as one (1), two (2) and five-thousand, six-hundred and seventy-eight (5,678); and three (2) introduces the opportunity to introduce a disagreement between the spelt-out number and the number number.

I agree w mintjulep, and would only add I was taught to use words if the numeric value is at the start of a sentence... "Two started their 10 year sentence"??

Don't remember where I got this from, but remember being told that parentheses are used only for numbers representing a quantity.  The number is spelled out and then the numeral in ().  Makes no sense now that I think about it but it has stuck with me.

I've been reading a lot of legal documents lately (regulations, legal opinions on regulations, and case law on previous regulations) and I've seen: (1)numbers as list-designators not spelled out; (2) numbers as quantity-designators less than ten (10) spelled out and put in parentheses; and (3) numbers greater than ten (10) as quantity designators just with numerals.  I find the "ten (10)" constuct to be easy to confuse with the list designators.  

None of this is perfectly consistent, but that seems to be the tendency.

David

I see parenthesis used more often to express alternate units. The example sentence should probably offer an equivalent number of liters (litres) for this international forum. Could get a bit confusing with all those parenthesis.

I tend to default to the U.S. Government Printing Office Style Manual.  I believe the general guidance is (excluding the probably dozens [12s?] of exceptions):

Never start a sentence with a numeral.  Spell it out.
Do not repeat spelled-out numbers with numerals.
Spell numbers out less than 10.
If there are two or more numbers in a list, and one of them is greater than 10, use numerals for both.

Applied to engineering, I use numerals for anything that is a measurement.  I'm not sure if that's an accepted rule, but it seems to make sense.

I see legalese creeping into engineering communication all the time.  Engineering communications should be clear, concise, and accurate--nothing else.  It almost seems as though engineering writers see things in legal fine print and think, "Gee, that looks professional.  If I write like this, I can't get sued."

WHEREAS legalese writing looks fancy, an engineer's time is better spent writing language that is easy to understand.  Language that is easy to understand is generally harder to misuse.
 

I agree with John's wife.  Also, use one or the other but not both (named and parenthetical numbers) together in a report.  The reason being is that sometimes when a report is edited, one gets changed and the other doesn't.  Not good for liability purposes!

I hate the notion of rules on numbers less than or equal to 10 having separate formats.  First of all it can't be reasonably followed - "I ran the race in six-point-two minutes" doesn't make sense.  So, therefore, we are talking about whole number usage only, I guess. Then there's the range issue - It'll likely take between nine and 11 minutes for the average runner to finish this race.  That just messes up the eye!

Sometimes style sheets need to be adaptable.

f-d

¡papá gordo ain't no madre flaca!

f-d
In your first example above, I think that the proper way to present the information would be "six minutes twelve seconds."  You could also write: "I ran the race in 6:12," but that assumes that your reader will know that you mean minutes and seconds rather than six hours and twelve minutes (which might apply if you were running a marathon).

As to your second example "...between nine and 11 minutes," as Erdbau mentioned above, if there are two or more numbers in a list, and one or more of them are over ten, you use numerals for all of them, so the correct way would be: "between 9 and 11 minutes."   

Just saw the thread, and happened to be working on a similar issue.  I use parenthetical numerals when ordering parts with a measurement in the part name, e.g., Ten (10) 1" Sched 80 CPVC couplings.  This minimizes problems like getting a 24" flange when you wanted two (2) 4" flanges.

Matt

Quality, quantity, cost.  Pick two.

But if you write the quantity in words, you don't need to write the numeral at all.  If you feel you really need to have a numeral, you can write: 4" flange x 2,  or 4" flange, 2 each.   

In some contexts, I see parenthetical numbers used as a sort of (modulo 10) checksum rather than just to repeat the initial figure - an example might be:

LEAK RATE ASSESSED STEADY AT 5(5) LITRES PER MINUTE. THEREFORE ANTICIPATE COMPLETE LOSS OF COOLANT IN APPROX 48(2) HOURS.

If you don't explain which system you're using, not only does it lose all value as a means of spotting errors, but it also leads to confusion.

A.

I am pretty sure we have lawyers to blame for the redundancy of using words and parenthetical numbers together. Even if they're not to blame, I propose to do it anyway.

When I started in engineering in 1980, our bid forms required the contractor to write out the unit cost for each item, then write the numerical values for the unit cost and the extended amount.  The total amount bid was also required to be written out and expressed with numbers. The bid form stated that words governed over numbers. As you can imagine, it was quite time-consuming to complete a bid form with 30 or 40 or 50 items, which was typical for the projects we were doing.

In the pre- and early-spreadsheet eras, about half of the bid forms I reviewed had at least one discrepancy between the words and numbers. As soon as I saw the number of errors drop to almost zero, I eliminated the words part from my bid forms. I actually had several contractors call to thank me.

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

I've been taught that any number that can be written with just one word should be written as text, except where because of customary use or clarity using numericals is recommended.

So: eleven, twelve, thirteen, fourteen... should be written with letters.

The rest of the cases were already discussed earlier.

saludos.
a.

I agree with John Baker's wife too.
The only exception would be when a check is less than ten dollars then you still need to write it out.