Don't panic—your Excel isn't broken. If your column letters suddenly turn into numbers, you've stumbled into R1C1 mode. While it looks like a glitch, it's actually a high-level tool that lets you ...

I used to play formula roulette every time I dragged the fill handle, hoping Excel wouldn't misinterpret my intentions. Was I supposed to lock the column, the row, or both? Then, the dollar signs ...