1 550 billion

16:38 Nov 23, 2020 

Hi Juan,
We used to use the 12 zero billion in the UK, but it got confusing with the US use of the 9 zero billion. At one point, it depended on the context, whether it was money or measuring something else - really confusing. I don't think any fields use the 12 zero billion in the UK nowadays.
And I reckon Cristina may well be asking because she is unsure of this point, so your answer in number form is correct because it's a concise, conclusive solution to her doubt. ;@)

16:30 Nov 23, 2020 

Hi María,
We've used the 9 zero billion in the UK for quite some time now, so I would guess it's a moot point. But it is definitely worth mentioning.

15:34 Nov 23, 2020 

Cristina, podrías decirnos de dónde es el texto? Lo pregunto porque su uso en el inglés americano y británico es diferente.
bil•lion /ˈbɪlyən/ n.[countable], pl. -lions, [or, after a number] -lion, adj.
n.
a cardinal number represented in the U.S. by 1 followed by 9 zeros, and in Great Britain by 1 followed by 12 zeros:the sum of two billion dollars

14:14 Nov 23, 2020 

You're right, Neil. I didn't really pay attention to the verb "spell out", because I was myself wondering how much is 1,550 billion, so I verified directly if the billion on the long scale (12 zeros) was still used in Great Britain, but it seems it's not. So, if we use billion in English nowadays I suppose we have to add 9 zeros. Thank you for your confirmation.

14:10 Nov 23, 2020 

Cristina, what do you mean by spelt out?
In my book when you spell something out you use letters and words, but maybe you mean like Juan Manuel suggests and actually you want to know how many zeroes the number has.
Juan's suggestion is correct by the way, if that's what you are asking.
;@)