Permutation!
Probability
Level
3
How many numbers between 1000 and 10,000 are there such that their digits are no more than 4, 5, 6?
Examples are 456, 546, etc.
The answer is 81.
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1 solution
It is a four digit number and for each place we have three choices (4, 5, 6). So we can fill the four places in 3^4 = 81 ways.