9 and 99
9870
9.....??
9
The largest single digit composite number is 9. The largest prime number is 17 million digits long. The definition of a composite number is any number that has at least one positive divisor other than one or the number itself (it is not a prime number). The largest composite digit is therefore longer than the largest prime number by at leaf +1.
9 and 99
99 + 9 = 108
The largest one digit number that has three factors is 9. Its factors are 1, 3, and 9.
It is 9999 (if a one is added, it becomes a five digit number: 9999 + 1 = 10,000)
9870
It is: 8
9.....??
9
The largest single digit composite number is 9. The largest prime number is 17 million digits long. The definition of a composite number is any number that has at least one positive divisor other than one or the number itself (it is not a prime number). The largest composite digit is therefore longer than the largest prime number by at leaf +1.
Unless this is a trick question 9995 would be the largest 4 digit number with 5 as one of its digits
999 is the largest 3-digit number.
9797 is the largest two digit prime number.