Find number abc

Three older ladies were discussing the travails of getting older.

One said, "Sometimes I catch myself with a jar of mayonnaise in my hand, in front of the refrigerator, and I can't remember whether I was taking it out or putting it away."

The second lady said, "Yes, sometimes I find myself on the landing of the stairs, and I can't remember whether I was on my up, or on my way down."

The third lady chimed in, "Well, I'm glad I don't have those problems. Knock on wood." With that, she rapped her knuckles on the table, then said, "That must be the door. I'll get it."