2023 AMC 10B Problem 16

Define an upno to be a positive integer of 2 or more digits where the digits are strictly increasing moving left to right. Similarly, define a downno to be a positive integer of 2 or more digits where the digits are strictly decreasing moving left to right. For instance, the number 258 is an upno and 8620 is a downno. Let U equal the total number of upnos and let D equal the total number of downnos. What is |U - D|?

\textbf{(A)} 512 \qquad \textbf{(B)} 10 \qquad \textbf{(C)} 0 \qquad \textbf{(D)} 9 \qquad \textbf{(E)} 511

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.