Supposedly, Russian peasants perform multiplication in the following fashion: they write the two numbers which are to be multiplied at the top of two columns; then, they multiply the number in the right column by two, and divide the number in the left column by two – throwing away any fractional part – continuing until the number in the left col…

RussianPeasantMultiplication.java

public class RussianPeasantMultiplication
{
  public static int multiply( int l, int r )
  {
    int result = 0, lsb = l & 1;
    if( lsb == 1 )
      result += r;
    while( l != 0 )
    {
      r <<= 1;
      l >>= 1;
      lsb = l & 1;
      if( lsb == 1 )
        result += r;
    }
    return result;
  }
}