There are 24 combinations using each digit only once per combination: 135 137 153 157 173 175 315 317 351 357 371 375 513 517 531 537 571 573 713 715 731 735 751 and 753.
-8
9
it depends on which 8 numbers your talking about
If there are no restrictions on duplicated numbers or other patterns of numbers then there are 10 ways of selecting the first digit and also 10 ways of selecting the second digit. The number of combinations is therefore 10 x 10 = 100.
Using the formula n!/r!(n-r)! where n is the number of possible numbers and r is the number of numbers chosen, there are 13983816 combinations of six numbers between 1 and 49 inclusive.
-8
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
There are 840 4-digit combinations without repeating any digit in the combinations.
120 combinations using each digit once per combination. There are 625 combinations if you can repeat the digits.
9
It depends. If you can only use each number once, there are 720 combinations. If you can use numbers multiple times, then there are 1000 combinations, by using all numbers from 000 to 999.
15
10,000
It is: 9C7 = 36
it depends on which 8 numbers your talking about
If there are no restrictions on duplicated numbers or other patterns of numbers then there are 10 ways of selecting the first digit and also 10 ways of selecting the second digit. The number of combinations is therefore 10 x 10 = 100.
To calculate the number of different 4-digit combinations that can be made using numbers 0 through 9, we use the concept of permutations. Since repetition is allowed, we use the formula for permutations with repetition, which is n^r, where n is the number of options for each digit (10 in this case) and r is the number of digits (4 in this case). Therefore, the number of different 4-digit combinations that can be made using numbers 0 through 9 is 10^4, which equals 10,000 combinations.