Question 198047
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There are 10 ways ( 0 through 9 ) to select the first number.  Once the first number has been selected there remain 9 ways to select the second number because of the restriction on repetition of digits.  Then 8 ways for the third number and 7 ways for the fourth number, hence:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 10 \times 9 \times 8 \times 7]


You can do your own arithmetic.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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