the answer is = first 2-digit number by using 48= 28,82 and in 3 digit is=282,228,822,822
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
There are twelve possible solutions using the rule you stated.
10,000 combinations.
There are 5,461,512 such combinations.
There is only 1 combination.
216
64
Using the eight digits, 1 - 8 ,-- There are 40,320 eight-digit permutations.-- There is 1 eight-digit combination.
There are 840 4-digit combinations without repeating any digit in the combinations.
There are 5,040 combinations.
120 combinations using each digit once per combination. There are 625 combinations if you can repeat the digits.
There are 210 4 digit combinations and 5040 different 4 digit codes.