The Mac speech synthesizer has to be aware of context as it speaks. Otherwise, if you had “$1000” in your sentence it would say something like “dollar sign one thousand”. I get that.
Did you know that it can speak roman numerals? We stumbled on one phrase that triggers it: “Mac OS X”. Specifically “OS” triggers it. The numerals must be uppercase as well. I imagine that when Apple demos the Mac speech synthesizer, they want it to be able to say its name correctly. However, you can also substitute any other valid Roman Numeral for the “X”. How sophisticated is the Roman Numeral processing? 1987 seems to be complicated enough for me, but my Mac handles it with ease.
Try the say command in Terminal: say “OS MCMLXXXVII”. Cool.