How many different combinations of 7 numbers are there?

Answer 1

9999999

Answer 2

5040, the different number of combinations, or permutations, can be calculated using the nPr button on a scientific calculator, and finds the number of ways a subset of r elements can be ordered from a set of n elements using the function n!/(n-r)!

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The answer is wrong. A permutaion is not the same as a combination. In permutations 123 is differrent from 213, or 312, or 321. But they all are the same combination.

So, what you want is not the nPr button but the nCr button.

nCr = n!/[r!*(n-r)!]

So, from the 10 digits available, there are 10!/[7!*3!] = 120 combinations of 7 numbers.

Answer 3

7