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How many 3 digit palindrome numbers can be formed by using digits 1, 2, 3, 4, 5 and 6?
How would the total number of palindrome numbers change if there were only 4 digits to choose from?
If there were only 4 digits to choose from, say, 1, 2, 3, and 4, then the same two cases apply. There are 4 options for the repeating digit and 3 options for the non-repeating digit in the first case. In the second case, there are 4 options for the first digit and 3 options for the third digit. Therefore, the total number of 3 digit palindrome numbers that can be formed using digits 1, 2, 3, and 4 is 4*3 + 4*3 = 24.