To me, two hundreds of books or one hundred of books is natural.
Why is “one hundreds” in the picture in plural form?
To me, two hundreds of books or one hundred of books is natural.
Why is “one hundreds” in the picture in plural form?
One hundreds (plural) is correct on the label because each individual item in the bundle is a single one hundred - so more than one of them is some number of one hundreds (plural). The point of the label is to identify the denomination of the notes (bills).
The same principle applies to bundles of other denominations, for example a bundle of five dollar notes would be labelled "Fives". Take one note out and you have one five; take two out and you have two fives (plural).
If you withdrew $450 from your bank account you could say to the teller, "please give me three one hundreds, two fifties, and five tens".
To me, two hundreds of books or one hundred of books is natural
We wouldn't say "two hundreds of books", we'd just say "two hundred books". But anyway, that is a different situation where the thing being counted is books, whereas in your picture the thing being collected (not counted) is bank notes each of which is called a one hundred.
What is shown is a stack of one hundred one-hundred-dollar bills. One of them would be a one-hundred-dollar bill. A short name for such a bill is a one-hundred. Thus, a stack of them is a stack of one-hundreds. Probably, the person who designed the label was not into the finer points of punctuation and so omitted the hyphen.
These appear to be American banknotes, which look like this (from the U.S. Treasury’s currency education page):
This banknote says “ONE HUNDRED DOLLARS” and is formally called a one-hundred-dollar bill. This is using a slightly unusual term for one: calling a one-hundred dollar bill “a one hundred,” and therefore, a stack of them “one hundreds”. This person would probably call that, “ten thousand dollars in one hundreds,” or “a stack of a hundred one hundreds.”
It would be more common to call them “hundreds,” as in, “I’d like to take out a thousand dollars, in hundreds.” However, something like “five hundreds” might then be ambiguous, as it could be referring to either five notes denominated 100, or to notes denominated 500. (U.S. currency does not happen to have any notes whose denominations would have this problem, but some others such as the Euro do, and foreign travelers might not be as familiar with U.S. currency.) If i had to speculate, that might be why the bank avoided that usage.
This note is called many other slang terms, too. For example, the song and movie from the late ’90s, “All about the Benjamins,” is talking about hundred-dollar bills with Benjamin Franklin’s face on them, which was the largest bill then in circulation (so it’s talking about the lifestyle of someone who carries around large amounts of cash). A Franklin is another, and so is a C-note.