It's actually infinite.
you can keep going forever using subtraction, here's an example.
one billion minus nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred.
^- equals 100, and has one hundred characters.
onehundredminusseventyfour is 26 characters and evaluates to 26. It wouldn't be hard to go beyond that.
onethousandminusninehundredsixtyfour is 36
Just for fun:
105 + 40^0 = 106.
Come to think of it, this contest is going to end in an arbitrarily large number as the winning entry just because someone's going to figure out how to create a word problem with no repeating word, and then it's going to be a hassle reading through it to verify that it doesn't have any spelling, grammar, or punctuation errors while still using exactly one of each English word (which, I might add, is a constantly expanding language.)
in wabambuule, mystical land o' honeycombs and rabbits, a tribe of pixies lives. They require thirty one trombones. sprites from the neighboring borough need two hundred three. how many total musical instruments are needed? give your answer to nearest hundredth decimal place
a few notes:
1. Yes, I made up a name but any word will fit there.
2. There are still quite a few synonyms for fairies I can use to expand this.
3. I have any number of musical instruments to add.
You could also just say --------...---infinity, where you have an infinite number of negation operators (which don't count as a repeated word, and are not expressly forbidden, and are not expressly stated not to count), but I'm going to assume that's out of the bounds of the problem because the whole point was to remove some of the loopholes that made the original problem go infinite.