Question 1191853:
If repetition is not allowed then how many numbers between 2000 and 3000 can be formed using the digits from 0 to 7?
Answer by math_tutor2020(3817)   (Show Source):
You can put this solution on YOUR website!
The left most slot (thousands digit) can only be a 2 if we want the number between 2000 and 3000.
The set {0,1,2,3,4,5,6,7} is reduced to {0,1,3,4,5,6,7}
The original set had 8 items in it and the new reduced set has 7 items in it.
For the second slot, there are 7 choices to pick from (pick anything in that reduced set).
Then the third slot has 7-1 = 6 items to pick from if we aren't allowed to repeat digits.
Lastly, the final slot has 6-1 = 5 items to pick from.
Multiply those values: 7*6*5 = 42*5 = 210
Answer: 210
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