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Count possible phone numbers before excluding the correct one

A girl wishes to phone a friend but cannot remember the exact number. She knows that it is a five-digit number, that it is even, and that it consists of the digits 2, 3, 4, 5 and 6 in some order. Using this information, find the largest number of different wrong telephone numbers she could try.

[2002/I/17(b)]

CJC · Discussion · Question 2

Start with the even final digit.

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