A palindrome is a word or a number that reads the same forward and backward. For example, 2442 and 111 are palindromes. If 5-digit palindromes are formed using one or more of the digits 1, 2, 3, 4, 5, 6, and 7, how many palindromes are possible? Answers:  A) 35  B) 49  C) 105  D) 255  E) 343
There are 7 choices for each of the first three digits.   The number of possible palindromes is 7^3=343.   The answer is 343.
<result>E</result>
A palindrome is a word or a number that reads the same forward and backward. For example, 2442 and 111 are palindromes. If 5-digit palindromes are formed using one or more of the digits 1, 2, 3, 4, 5, 6, and 7, how many palindromes are possible?