I always use good ol' mechanical pencils, particularly Twist Erase or BiC with 0.7 lead.
I still prefer to write out mathematical proofs sloppily (and with a lot of the nitty-gritty details missing) in a scrap notebook, then write it more nicely (filling in all details) on computer printer paper, and then…
I always use good ol' mechanical pencils, particularly Twist Erase or BiC with 0.7 lead.
I still prefer to write out mathematical proofs sloppily (and with a lot of the nitty-gritty details missing) in a scrap notebook, then write it more nicely (filling in all details) on computer printer paper, and then…