One of the answers in a reading exercise in my class today was:
- 100,000,000,000,000,000,000
… which was the value of the highest denomination note ever issued. It was a 100,000,000,000,000,000,000 Pengo note, issued by Hungary in 1946. The students in my class wanted to know how they could say that last sentence in words in English. So I told them that I didn't know. They pointed out to me that if they wanted to read this bit of writing to someone they'd want to be able to use the words. Fair point.
Can anyone help?
[In case you're interested, a 100,000,000,000,000,000,000 Pengo note was worth about $0.20!]
Best Answer
It's:
or:
The words for very large numbers
If you're wondering how to form other huge numbers like this, here's the pattern:
A thousand thousands is a million: 1,000,000.
A thousand millions is a billion: 1,000,000,000.
A thousand billions is a trillion: 1,000,000,000,000.
A thousand trillions is a quadrillion: 1,000,000,000,000,000.
A thousand quadrillions is a quintillion: 1,000,000,000,000,000,000.
A thousand quintillions is a sextillion: 1,000,000,000,000,000,000,000.
And so on. The part before -illion is the Latin prefix for the number of times you went through the process of multiplying by a thousand. So, you can continue to septillion, octillion, nonillion, decillion, undecillion, duodecillion, and so on forever.
Within the scale defined by one of these huge units, you multiply by a number from 1 to 999 in the usual manner, by putting the multiplier ahead of the unit, and you add smaller numbers by putting them after the unit, in the same manner as for thousands:
The usual customs for "hundred" apply:
Exponents
When you work with these numbers on a daily basis like I do,* you soon find that they become rather unwieldy, at least until you get up to a centillion pengős.† In the physical sciences, if not in economics, one normally writes and pronounces these numbers using powers of ten. A quintillion is 1018, which you pronounce like this:
In scientific notation, you always choose an exponent large enough so the multiplier has one digit to the left of the decimal point, like this: 2.15 ⨉ 1017. That's pronounced:
If the multiplier is exactly 1, you can omit it in speech. So:
Does anybody really say “quintillion”?
“Quintillion” is an obscure word, though not much more obscure than “quadrillion”, which often gets totted out when government budgets and monetary inflation make news. A fluent speaker can guess it from the pattern of “billion”, “trillion”, etc. Here are a few samples to illustrate typical contexts where people really use it to communicate (that is, not just to talk about words for huge numbers, which might be its most frequent use):
Often when “quintillion” appears in print, it’s accompanied with an explanation. Usually when I’ve seen it used without explanation, it’s been in the context of economics. Presumably that crowd is well accustomed to talking about vast sums of money.
Long scale and short scale
Notice that in the Indonesian budget described above, “quintillion” occurs with multipliers greater than 999. That suggests that they're following the “long scale” system, in which each successive ‑illion is a million times greater than the previous one. That's an older usage, now nonstandard in English in all countries, but some people still use it, especially in countries like Indonesia where the dominant language follows the long-scale system. See kasperd's answer for more about that.
*Just kidding.
†When you get up to a centillion pengős, you're talkin’ real money.