Can anyone tell me what the line of numbers across the bottom of a copywrite page mean?

Question

Someone asked me and I am not sure. It would say 30 29 28 27 26 25 24 23 22 (example - numbers may be different). Thanks!

Answer 1

The lowest number is the edition number. For each edition a number is removed. It is left over from the time when the books were on printing plates.They would grind off the lowest number when doing a new printing.

Answer 2

the numbers are to do with, what number printing it is.

a publishing company may have paid for the licence to print a book 10 times say, with each print run could be a million copies or more

so 2 10 9 8 7 6 5 4 3

i believe is a second printing, or something like that