5
45.
There would be 9*9*9*9 or 6561 combinations.
-8
Exactly 3,628,800, or 10!.
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
The answer will depend on how many digits there are in each of the 30 numbers. If the 30 numbers are all 6-digit numbers then the answer is NONE! If the 30 numbers are the first 30 counting numbers then there are 126 combinations of five 1-digit numbers, 1764 combinations of three 1-digit numbers and one 2-digit number, and 1710 combinations of one 1-digit number and two 2-digit numbers. That makes a total of 3600 5-digit combinations.
To calculate the number of 6-digit combinations using 20 numbers, you can use the formula for combinations, which is nCr = n! / r!(n-r)!. In this case, n = 20 (the total number of numbers) and r = 6 (the number of digits in each combination). Plugging these values into the formula gives us 20C6 = 20! / 6!(20-6)! = 38,760 unique 6-digit combinations that can be formed using 20 numbers.
There are 1140 five digit combinations between numbers 1 and 20.
If you are able to repeat numbers you would take 6 * 6 * 6 = 216 combinations. If you are not able to repeat numbers you would take 6 * 5 * 4 = 120 combinations.
There are 840 4-digit combinations without repeating any digit in the combinations.
You would get 4!/2! = 12 combinations.
7
56 combinations. :)
Any 6 from 51 = 18,009,460 combinations
5
45.