In EXCEL, the cell is set as text, and 14 digits are entered. Why don't the cells below the drop-down box increase in turn?

Because the program does not calculate text. If increment is to be realized, it can be realized by formula, but the cell format should be "regular". The formula is as follows:

= "888888"& text (line (a 1), "000000")

Just fill out the formula and copy it down. The first six eights in the formula are expressed in words, and the actual situation is changed by LZ himself.