Comment by clausok

I encountered exactly this when my brother went to film school. The students would rotate roles and it was his turn to be the producer. One day I came home from work and he was having problems with his Excel-based budget sheet. I noticed that his row of sums at the bottom of one sheet had hard-coded values rather than formulas. Thinking he had inadvertently pasted over them, I told him, "Look, you killed your formulas." "What are formulas?", he asked. Turns out that he had been tallying up the columns with a calculator and then typing those totals into Excel.