20KiB, 600x600, B03F017917832D6BF6FD9515680FB2900CBF2583_large.jpg View SameGoogleiqdbSauceNAO Anonymous Sun 30 Aug 04:30:15 2020 No.12064921 ViewReplyOriginalReport Quoted By: anybody on /sci/ into speed multiplication? I know it's a party trick, but I've always thought it would be fun to learn some techniques. any methods or books you like?