I started programming on the BBC model B. You had to number each line by hand. The convention was to write the line numbers in steps of 10. Then as you went back and added lines, you'd run out of gaps to fit your lines in. Then you had to use the RENUMBER command and all the lines would be renumbered in steps of 10 again.

It was a great breakthrough to me when it was realized that line numbers could be derived from the text rather than assigned to the text. I suppose that was only possible when things like the GOTO statement didn't accept a line number.

I must have been about 11 when I started. Happy days!