Long division with messy numbers?
Try short division instead -- far simpler !!
I found this recently.
I illustrate below with a couple examples.
Dr. Aitken was both a mathematician and a mental calculator. His prowess is described in the first link below (about halfway down the page).
https://mathshistory.st-andrews.ac.uk/HistTopics/Mental_arithmetic/
And here’s a second link — well worth reading.
https://cowles.yale.edu/sites/default/files/files/pub/d17/d1750.pdf
