How many numbers?
Probability
Level
2
What is the total number of integers that can be formed by concatenating the digits and at most once?
The answer is 11743.
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1 solution
1 digit = 7 numbers
2 digit = (6)(6) = 36 numbers
3 digits = (6)(6)(5) = 180 numbers
4 digits = (6)(6)(5)(4) = 720 numbers
5 digits = (6)(6)(5)(4)(3) = 2160 numbers
6 digits = (6)(6)(5)(4)(3)(2) = 4320 numbers
7 digits = (6)(6)(5)(4)(3)(2)(1) = 4320 numbers
number of digits = 7 + 36 + 180 + 720 + 2160 + 4320 + 4320 = 11743 numbers