MathDB
2023 Individual #11

Source:

April 26, 2023
2023 Individual

Problem Statement

A semi-palindrome is a four-digit number whose first two digits and last two digits are identical. For instance, 23232323 and 57575757 are semi-palindromes, but 10011001 and 23242324 are not. What is the difference between the largest semi-palindrome and smallest semi-palindrome?
<spanclass=latexbold>(A)</span>7979<spanclass=latexbold>(B)</span>8080<spanclass=latexbold>(C)</span>8181<spanclass=latexbold>(D)</span>8484<spanclass=latexbold>(E)</span>8989<span class='latex-bold'>(A) </span> 7979\qquad<span class='latex-bold'>(B) </span> 8080\qquad<span class='latex-bold'>(C) </span> 8181\qquad<span class='latex-bold'>(D) </span> 8484\qquad<span class='latex-bold'>(E) </span> 8989