An Ancient greek or Roman would have lacked paper. Using the available paper on arithmetic would have been seen as an inordinate waste of dies and paper.
For temporary purposes, they usually wrote on wax tablets with styluses, which could be easily melted and re-molded for reuse. They came in little boxes with a protective cover and were used for temporary records and drafts and personal letters: https://upload.wikimedia.org/wikipedia/commons/1/11/Table_wi...
And there's always sand! It's probably apocryphal but the legend is that Archimedes was slain by a Roman soldier during the taking of Syracuse when he objected -- "Don't disturb my circles!" -- to how the soldier marched through his trigonometry problems.
