Most insertion commands — like i, I, a, A, o, O, and so on — accept a count. If you type a count in normal mode before hitting an insertion map, like 10A, then type your text, the insertion will be repeated that many times.
This means that you can do things like:
- 3Afoo<esc> to append foo to the current line 3 times
- 10ohello world<esc> to add 10 new lines with the text hello world
- 5I--<esc> to prefix the current line with 5 - characters
Try it in the editor!