I picked up the letter O.M. A girl I had taught in a 5th grade class in N.C. 55 years ago. As I was to watch the children the next day, I asked one to show me where they were in arithmetic. One he got right sum 1884 but the other was 118. I pointed out that it shouldn't be so much smaller. He remembered there was 1 to carry . I told him to add the last column again. This time he got 2480.