6. (10 points) There are some playing cards on the table. Jia took a prime number of cards, leaving a number that is a multiple of 5; Yi then took a prime number of cards, leaving a number that is a multiple of 3; Bing took a prime number of cards, leaving a number that is a multiple of 2; Ding took a prime number of cards, leaving a prime number of cards for Wu. It is known that the number of cards taken by Jia, Yi, Bing, Ding, and Wu is decreasing. How many cards were there on the table at least? $\qquad$
【Answer】Solution: The following table is derived by successive inference.
\begin{tabular}{|c|c|c|}
\hline & Remaining & Taken \\
\hline Wu & & 3 \\
\hline Ding & 10 & 7 \\
\hline Bing & 27 & 17 \\
\hline Yi & 40 & 19 \\
\hline Jia & 63 & 23 \\
\hline
\end{tabular}

All the data above meet the requirements of the problem, and they are the smallest values.
Therefore: The answer should be 63.