# How should I express large numbers with a combination of numerals and a word?

I am working on a translation of a document from Korean to English. There is a table containing large numbers (given in trillions and hundred millions), written like so:

So the number expressed above is 2 trillion, 474.5 billion (2 474 500 000 000).

The numbers should be expressed similarly in the translated document using a combination of the five numerals and a corresponding word (trillion or billion). The sticking point for me here is that I can only recall seeing large numbers followed by "million," "billion," or "trillion" written out to two (maybe three) decimal places:

3.54 trillion

Taking that into consideration, I'm considering the following options:

• 2.4745 trillion (seems "cleanest" but the number of decimal places makes me uncertain)
• 2474.5 billion
• *2 trillion 474.5 billion (seems unwieldy and unlikely to be a conventional form)

Of those three, the first one (2.4745 trillion) seems likely to be the most correct, but also seems a bit odd with four decimal places. This leads me to wonder if it's unusual but still an acceptable form.

I searched around online, but I couldn't find a credible source providing conventions/standards for how many digits out you can take a number when it's expressed this way, if in fact there are any.

How should a large number be expressed with a combination of numerals and a word when there would be four or more digits following the decimal? (Is there a standard for this?)

Note: I'm looking for an answer providing a credible source, not simply stating "write it this way."

• Why should the number of decimals in 2.4745 make you nervous? If that's the precision you need, that's what you use. And if you say you see so many numbers with two decimals, that's because those numbers often refer to money, in dollars and cents. Commented Nov 22, 2016 at 7:40
• I don't think any style manual will tell you exactly what you are supposed to do. What I wonder is why you can't round it up.
– user140086
Commented Nov 22, 2016 at 7:41
• I see. Then, it's your call. I would go for 2.47(45) trillion or 2.4745 tillion.
– user140086
Commented Nov 22, 2016 at 7:48
• Standard-wise I don't think such one may even exist - we talk 2 different things here: scientific/technical precision and representation of numbers (and sure there're standards in this from say IEEE) and language specific conventions of naming/saying/writing numbers.And I stress 'specific' - what is billion there is milliard here, what is comma separator there is a dot here. So from scientific POV use fully written number without words, from linguistic standpoint - write the way the target audience will find most convenient and usual. In my 2 MSc Eng degrees never saw any of 3 ways you suggest
– Yuri
Commented Nov 22, 2016 at 8:37
• Actually the least weird to me is the 2nd one as we, engineers, are used to base 10 numbers to split/overflow at dot (3 decimal places). But given that your audience is the financial domain I am not of a good reference here cause even 100% valid number representations in financial reports seem strange to us.
– Yuri
Commented Nov 22, 2016 at 8:53