As a string, the largest number is 7111111.
It is 97.
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.
An eight digit number with one zero cannot remain the same when its digits are reversed. It must have an even number of 0s.
In a proper fraction the numerator is smaller than the denominator. Since every two-digit number is larger than every one-digit number, there must be a one-digit numerator and two-digit denominator comprising 3 digits total. The greatest fraction will be the one with the largest possible numerator and smallest possible denominator. Choose a numerator of 9 (the largest one-digit number) and a denominator of 10 (the smallest 2-digit number). All 3 digits are different. The answer is 9/10.
Largest three digit number is 999 and we see that it is odd. One less than that is 998 and it is even and it is also three digits. No other 3 digit number is larger than 998 while being even.
9 and 99
It looks like you're asking what is the largest 4-digit number which has four 4's for digits - with a four digit number using four 4's, there is only one such number: 4444. Maybe I'm not understanding the wording of your question.
Any number that has 4 or 5 digits. A digit in a number is one number place. 1 has 1 digit, 11 has 2 digits, 111 has 3 digits, and so on.
1 The largest five-digit number is 99999 and the smallest six-digit number is 100000, so the difference is one. If you're just looking for an answer to a homework question, that's all you need. For the brainy: Suppose the answer was greater than one. That would mean that there are one or more numbers between the largest five-digit number and the smallest six-digit number that cannot be written with either five or six digits. Either they would have to be written with four or fewer digits, which would make them smaller than any five-digit number, or with seven or more digits, which would make them larger than any six-digit number. If the answer was less than one, it would mean that it would be possible to have a five digit number that was greater than a six-digit one. So the answer must be one.
99 + 9 = 108
Any 5-digit number is greater than a 4-digit one.
974. If you mean the largest one with ONLY the digits 4 and 7, then 774. If it can only contain 7 and 4 but doesn't have to have both, then 777.
One digit. 1000 - 999
We call them by the number of their digits. Two-digit number, three-digit number and so on.