0
I don't understand the point or meaning of this question but I have provided a few answers below. I suggest you consider posting future questions in a less ambiguous turn of phrase.
1) For Natural numbers, there are 9 (or 10 if you include zero): 1 to 9
2) If you include negative numbers then there are 18 (or 19 if you include 0)
These answers are all in base-10. Thus it is a silly question as a digit is merely a symbol; if you used base-16 (hexadecimal) then there would be 16 single digit numbers etc. A 'digit' is also not a necessary concept for a number system as a digit is only relevant in a number system that is based on a repeating series of characters.
What else can I help you with?
How many 5 digit numbers have exactly two sevens in them?
Excluding numbers with leading 0s, there are 6804 such numbers.
How many 3-digit numbers have exactly 2 digits that are the same?
1
How many 3 digit numbers have 2 of the same digits?
Exactly 2: 243 of them.
How many 3-digit numbers have exactly two sevens in them?
Leaving out 077, since it is actually a two digit number, the answer is 35.
How many 10 digit combinations are there for the numbers 0 through 9?
Exactly 3,628,800, or 10!.
How many 5 digit numbers contain exactly two 7 in them?
There are 6804 such numbers.
If using 7 single digit numbers how many different combinations can you get?
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
How many numbers exactly have 1 digit?
the right answer is 10 cause there is o,1,2,3,4,5,6,7,8,9 so there 10 numbers in total which have 1 digit
How many 5 digit numbers have exactly two sevens in them?
Excluding numbers with leading 0s, there are 6804 such numbers.
How many four-digit numbers are there between 500 and 3000?
If you include the number 3,000, there are exactly 2,001 4-digit numbers between 500 and 3000.
How many 3-digit numbers have exactly 2 digits that are the same?
1
How many 3 digit numbers have 2 of the same digits?
Exactly 2: 243 of them.
How many 3-digit numbers have exactly two sevens in them?
Leaving out 077, since it is actually a two digit number, the answer is 35.
How many whole numbers from 1 to 100 contain the digit 3 exactly once?
18
How many 10 digit combinations are there for the numbers 0 through 9?
Exactly 3,628,800, or 10!.
How many 3 digit numbers can be formed from 6 single digit numbers if repeats are allowed?
if the repetition is allowed the there is 6*6*6 possible ways = 216
How many 6 digit numbers contain exactly different 4 digits?
There are 22680 numbers, excluding those with leading 0s.
