(1/3) Here's ChatGPT's proof that .999... is less than 1 [sic]: To prove that .999 is less than 1, we can use the fact that .999 is equal to 1 - (1/10) - (1/100) - (1/1000) - . If we add (1/10) + (1/100) + (1/1000) + to both sides of the equation, we get: