Test and analysis: Substitute 5298 into calculation, and rearrange the four numbers of 5298 into a four-digit 9852. Then 9852-2589=7263, rearrange the four numbers of 7263 into a four-digit 7632. Then 7632-2367=5265. Rearrange the four digits of 5265 from large to small into a four-digit 6552. Then 6552-2556=3996, rearrange the four digits of 3996 into a four-digit 9963. Then 9963-3699=6264, rearrange the four digits of 6264 from big to small into a four-digit 6642. Rearrange the four numbers of 4 176 from large to small into four digits of 764 1. Then 764 1-1467 = 6 174, and rearrange the four numbers of 6174 from large to small into four digits of 7641. Then 7641-1467 = 6 174 ... It is known that after seven transformations, the four digits will eventually stop at a certain number 6174. In the same way.