How many combinations of numbers are there between 0 and 9?
How many combinations of numbers are there between 0 and 9? So there are 10,000 possible 4-digit combinations using the digits 0–9. How many combinations are possible with 2 numbers? So that means you need to know how many different permutations there are for each combination. If there are two numbers, there are two permutations per combination. Divide the possible permutations by number of permutations per combination: 2450 / 2 = 1225. How many combinations can you get with 9 numbers? Therefore, the total number of possibilities is given by 9×9! =3265920. Hence, 9 digit numbers of different digits can...