1. The problem states that Millie truncates the number $N$ to 1 digit and the result is 8. 2. Truncating to 1 digit means keeping only the integer part of $N$ and discarding all digits after the decimal point. 3. Since the truncated value is 8, the original number $N$ must be between 8 and 9 but less than 9 (because truncation removes decimals). 4. Therefore, the error interval for $N$ is $$8 \leq N < 9$$. 5. This interval means $N$ can be any number starting from 8 up to but not including 9, so truncating $N$ to 1 digit will always give 8.