You got your result: 27x34=918 Method 3: Rounding and Adjusting This method is fantastic when one or both numbers are close to a multiple of 10 (e.g., 19,21,48,52). You round, multiply, and then ...

Schönhage and Strassen predicted that an algorithm multiplying n -digit numbers using n * log (n) basic operations should exist, Harvey says. His paper is the first known proof that it does.