# Mathematicians who often didn't use notebooks/devices to work?

Newton was known to keep manuscripts of his thoughts and workings on math/physics (and even more related to religion) which are kept in Cambridge I believe.

My question is, are there examples of the contrary; mathematicians who are thought not to have made extensive use of physical media (parchment/paper/computers) to do their work? Instead, they may have had strong mental "note-keeping" skills so to speak, as well as strong mental imagery.

They could still publish their results of course.

I originally posted this question on math.stackexchange, but closed it to post it on HSM. Some of the comments I received were broadly:

• Euler continued to work after becoming blind. In fact, half of his work was published after becoming blind.
• Ramanujan mostly wrote only his final results in his notebooks.

One other mathematician who was blind that I've come across since originally asking this question is Lev Pontryagin.

• Until 18th century paper was expensive. I suppose for this reason Fermat wrote on margins of Diophantus book, and Newton used a single notebook for all his records during his 5 years of studies in Cambridge. Most mathematicians had to keep most of their results in their memory. – Alexandre Eremenko Nov 4 '20 at 23:25
• Ramanujan famously did all his calculations and derivations on slate with chalk and only stored final results on paper. He couldn't not afford too much paper because of poverty and that's why resorted to chalk and slate. – Paramanand Singh Feb 18 at 3:24