There were 5 pieces of hard paper on the table. Take out several sheets from it, and cut each sheet into 7 smaller pieces of paper, and then put them back on the table, like this, take it out, cut it smaller, put it back; then take it out, cut it smaller, put it back; … Is it possible After a certain return, the number of pieces of paper on the table is exactly 1991?
桌面上原有硬纸片5张．从中取出若干张来，并将每张都任意剪成7张较小的纸片，然后放回桌面，像这样，取出，剪小，放回；再取出，剪小，放回；…是否可能在某次放回后，桌上的纸片数刚好是1991？
<gadget id="calculator">6 * 331</gadget>
<output>1_986</output>

<gadget id="calculator">1_986 + 5</gadget>
<output>1_991</output>

<result>1_991</result>