A palindrome is a number that reads the same when read from either end. For example, 12321 is a palindrome. A set consists of all the 3-digit palindromes whose product of digits has 1 as the unit digit. Select for Minimum the minimum possible value of the tens digit of any of the numbers in the set, and select for Maximum the maximum possible value of the tens digit of any of the numbers in the set. Make only two selections, one in each column.
Solution: Since the set consists of all 3-digit palindromes with the unit's digit of the product of 3 digits as 1
Let Hundred's place digit = X = Unit's place digit
and Ten's place digit = Y
Such that, the palindrome = XYX
with \(X^2\) * Y having 1 at the unit's place
Now, we need to find the minimum and maximum value of Y\(X^2\) can have values at the unit's digit as 1, 4, 5, 6 and 9
For the product of \(X^2\) and Y to have the unit digit = 1
only 1 and 9 are feasible as the rest of the numbers when multiplied with any value of Y, won't yield 1 as the unit digit.
So, 1 * Y should be 1
Hence, Y = 1; This is the minimum value
9 * Y should have 1 as the unit digit
Hence, Y = 9; This is the maximum value
Minimum value of Y = 1Maximum value of Y = 9
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