Translation:Eleven, twelve, thirteen.
ό,τι is not missing a space; that word is actually spelled like that!
The mark in the middle is not a κόμμα "comma" but a special mark called an υποδιαστολή ("hypodiastole") - it only exists in that word but it's not a punctuation mark but part of the word.
You can think of it, perhaps, like the apostrophe in a word such as "o'clock, fo'c'sle, e'er, it'll", which is similarly part of the word and not a punctuation mark "single quote".
So there's a difference between ό,τι "whatever" and ότι "that" (though people sometimes mix them up, and even this course might have the occasional error here -- please do report those if you know the difference between the two words!).
This item has been deleted but refuses to stay away. Can you tell us where you found it since it is not on the tree? Was it e.g. in a test out, or multiple choice, or strengthen skills etc. These are areas administered by the duobot which we have no control over but should be updated automatically. Thanks for including the date it also helps.
The parsing of the answers containing numbers seems to be very sensitive to commas and white space…
As Duolingo considers numbers expressed in digits as well as their alphabetic names, could it be that local preferences for math interfere?
(comma, period used in the expression of decimal numbers, e.g. 1,000.00 English, vs. 1 000,00 French ) …