## Problem

Observe the characteristics of the digits used in the minuend and subtrahend in equation (1). Try to use the patterns you identified in equation (1) to complete equation (2). What different answers can you write?

## Analysis

By analyzing and observing equation (1), we know from its calculation process that the 8 in the units place of the difference is obtained from 11-3, and the 9 in the tens place of the difference is obtained from 16-7. Therefore, when filling in equation (2), the 8 in the units place of the difference could be from 11-3=8. At this time, the digit in the units place of the minuend is 1, and the digit in the units place of the subtrahend is 3. Following the pattern presented in equation (1), we know the digit in the hundreds place of the subtrahend is 1, and the digit in the hundreds place of the minuend is 3. Verification yields 371-173=198.