Tonight someone tried to send me a spreadsheet, and it wouldn't open, so I asked if I could have the contents summarized in words. Then suddenly I realized: I could do math a lot better if I simply wrote it in words instead of numbers. 435 can turn into 453, but four hundred thirty-five will stay put. This is not much use to me as an adult, because I can either use a calculator or get someone else to do important math for me. But it would probably have saved me a lot of trouble in school. It wouldn't have fixed everything, but it would have made a big improvement.
I'm posting it here in case it would be useful for someone else.