1. The problem asks how to get the number 12 from 172, and then how to apply the same method to 180. 2. To find the relationship, we check the difference: $$172 - 12 = 160$$. 3. This suggests subtracting 160 from 172 gives 12. 4. Applying the same operation to 180: $$180 - 160 = 20$$. 5. Therefore, using the same method, the number corresponding to 180 is 20.