The following steps illustrate the results of repeatedly clicking the delete expression (or peel) button :
1. Start with a formula.
2. Select a formula element.
3. Click the delete expression button .
4. Click the delete expression again.
5. Click the delete expression again.
6. Click the delete expression again.
7. Click the delete expression again.
8. Click the delete expression again.
9. Click the delete expression again.