so 9999

So it is proved 1000 is the smallest 4 digit number in the number system. Question 6: What is the largest 4 digit number? Answer: The largest 4 digit number in the number system is 9999. If +1 is added to the number (9999) it becomes 5 digit number that is 10000 (a five-digit number). So 9999 is the largest 4 digit number in the number system. i get so weak in the knees lyrics