Final answer:
To form a four-digit even number using the given digits, there are 432 possible combinations.
Step-by-step explanation:
To form a four-digit even number using the digits (2, 3, 5, 1, 7, 9), the first digit has to be even. There are two even digits available, which are 2 and 5. Therefore, the first digit can be chosen in 2 ways. The remaining three digits can be chosen from any of the six available digits. So, the total number of four-digit even numbers that can be formed is 2 * 6 * 6 * 6 = 432.
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