An anecdote about the power of simple math and careful attention to detail, via Atul Gawande's book, "Better: A Surgeon's Notes on Performance (p. 254)":

MY THIRD ANSWER for becoming a positive deviant: Count something. Regardless of what one ultimately does in medicine—or outside medicine, for that matter—one should be a scientist in this world. In the simplest terms, this means one should count something…

When I was a resident I began counting how often our surgical patients ended up with an instrument or sponge forgotten inside them. It didn’t happen often: about one in fifteen thousand operations, I discovered. But when it did, serious injury could result. One patient had a thirteen-inch retractor left in him that tore into his bowel and bladder. Another had a small sponge left in his brain that caused an abscess and a permanent seizure disorder. Then I counted how often such mistakes occurred because the nurses hadn’t counted all the sponges as they were supposed to or because the doctors had ignored nurses’ warnings that an item was missing. It turned out to be hardly ever.

The numbers began to make sense. If nurses have to track fifty sponges and a couple of hundred instruments during an operation – already a tricky thing to do –it is understandably much harder under urgent circumstances or when unexpected changes require bringing in lots more equipment.

Our usual approach of punishing people for failures wasn’t going to eliminate the problem, I realized. Only a technological solution would—and I soon found myself working with some colleagues to come up with a device that could automate the tracking of sponges and instruments.

via "Better: A Surgeon's Notes on Performance"