Thankyou so much, but then you can tell me how would be the abbreviations for those quantities even if them exist or not?: quadrillion, quintillion, sextillion, septillion. how would abbreviate them you please? – ElektroStudios – 2013-08-17T14:01:48.800

@ElektroHacker I wouldn't abbreviate them with money, even if I had occasion to. With other matters I'd use decimal powers: 10^15, 10^18, 10^21, and so forth (or the superscripted versions, which won't display in a Comment). – StoneyB on hiatus – 2013-08-17T14:09:08.067

sorry if I'm annoying but the thing is I'm programming an application which has a function that returns the abbreviated quantity, for example with "1.200.000" the function returns "1,2 M", so I need to know how would be a "quadrillion, quintillion, sextillion and a septillion" abbreviated (using letters) for this problem. so I prefer to know the opinion of a U.S. person, rather than invent me the abbreviated letters based on their names. – ElektroStudios – 2013-08-17T15:43:08.573

@ElektroHacker As far as I know, standard abbreviations for those do not exist. You'd have to go to 'scientific notation'. Incidentally, in the English-speaking world we use the opposite convention for large decimal numbers: decimal fractions are marked with a . and successive thousand-multiples are marked with ,, thus: 1,000,000.05

Only just one more thing, exists a standard abbreviation for quantities less than a K of dollars?, for example for 999$? – ElektroStudios – 2013-08-17T17:40:49.180

1@ElektroHacker Nope. Three digits is too short to abbreviate. – StoneyB on hiatus – 2013-08-17T17:42:22.593

2@ElektroHacker: For dollars, it's written $999, not 999$. For cents, it's 99¢. – J.R. – 2013-08-17T19:19:48.413

Also, for what it's worth, I looked up b in the dictionary, and found it was an abbreviation for billion. Same for m for million. The dictionary I used didn't even list trillion as an abbreviation for t, even though I've seen it used before. You could always denote 1.2 quadrillion as 1,200 T. Who gave you these program requirements? – J.R. – 2013-08-17T19:25:26.193

@J.R. Thanks for the correction. The function it's just an own idea to simplify some monetary conversions in a program but seems hard than I've imagine because don't exists the required abbreviations to complete it. – ElektroStudios – 2013-08-17T19:50:36.433

Maybe there aren't any standard abbreviations, but that seems like a silly thing to thwart the development of a program. Just use Qd, Qn, Sx, and Sp. In the context of computer output, does it really matter if those are "standard" abbreviations? I wouldn't think so. – J.R. – 2013-08-17T20:02:35.263

FWIW, the only place I can actually remember seeing these abbreviations used is in The Economist, which is a British magazine. Most American publications, AFAIK, write out the quantity: "$1.2 million", "$3.4 trillion", etc. I think that many Americans would not understand immediately if you used abbreviations for these words without enough context for it to be obvious what they mean. – The Photon – 2013-08-18T01:34:39.280

Here's a list of articles about the national debt, which is good source for examples of American news sources discussing numbers in the range you are asking about: http://www.brillig.com/debt_clock/

It's also worth noting that, thanks to those pesky Romans and their numeral system, some people use "M" as a suffix to mean "thousand" (though this is now thankfully very rare) and "MM" to mean "Million" (still somewhat common). – Hellion – 2014-06-04T20:58:54.713

2This is incorrect. Money is not referred to with metric prefixes. – Aaron Brown – 2015-06-10T22:57:05.240

Hi, I believe that simply saying a solution is incorrect does not solve the problem. In this case, it seems that there is no absolutely correct answer. It is like choosing between bad and worse! If a programmer uses the above solution, does it cause any harm to the program or to the English language? if not, it seems logical to me to use a similar (or close) answer for a specific purpose. (I hope I could have explained what I mean through my poor English) – shirvanian – 2015-06-13T17:06:31.393

Sorry, perhaps incorrect was an unclear way to put it. There is a standard way of abbreviating large quantities of money, as detailed in StoneyB's answer, and the metric abbreviations are not the standard. Even in a programming context it's important to hold to known standards so that those who work on the code in the future can understand it easily. – Aaron Brown – 2015-06-14T03:37:57.490

I also prefer using a standard way but as StoneyB explained, "standard abbreviations for those do not exist". Then, J.R. proposed using "Qd,& etc. for this case and asked that: "In the context of computer output, does it really matter if those are "standard" abbreviations?" Then I asked myself why one should improvise a set of abbreviations if there already exists a very close set of abbreviations which we may use for this purpose? In an academic or expert context, which one is easier to understand: "one Peta or P dollars" or "one Qd. dollars"? (note that Qd. is not standard but P somehow is) – shirvanian – 2015-06-14T14:33:17.167

Yes, I would say using P, E, Z, Y would be OK for > 10^15, since there are no standard abbreviations. However, there are standard abbreviations for 10^3-10^12. That's the main part of your answer I disagreed with. – Aaron Brown – 2015-06-15T01:49:49.260

Thanks Aaron, among the abbreviations you disagreed, "K" is used nowadays in social networks to show the quantity of persons' fans; for instance we see somebody has "25K" audience or fans in instagram which of course does not mean "Kilo" but "thousand". So, this one may also be used in this context. – shirvanian – 2015-06-15T08:30:36.727