Really complicated Excel spreadsheets (although I'm actually a math girl at heart). It's sort of a love/hate/fear relationship with math. Wish I had had a more compassionate Calc teacher as a child.it was traumatizing. But it's never to late to "heal!
How to Create a Database from an Excel Spreadsheet
Excel Text to Columns is an Amazing tool that allows you to split the text in a cell into separate columns. You can use this to split names, urls, address, ids, or even convert numbers with trailing minus to negative numbers.