Re: If the first digit cannot be a 0 or a 5, how many five-digit odd numbe
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02 Dec 2022, 09:23
This problem can be solved with the Multiplication Principle. The Multiplication
Principle tells us that the number of ways independent events can occur together can
be determined by multiplying together the number of possible outcomes for each
event.
There are 8 possibilities for the first digit (1, 2, 3, 4, 6, 7, 8, 9).
There are 10 possibilities for the second digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
There are 10 possibilities for the third digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
There are 10 possibilities for the fourth digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
There are 5 possibilities for the fifth digit (1, 3, 5, 7, 9)
Using the Multiplication Principle:
= 8 * 10 * 10 * 10 * 5
= 40,000