I just learned that there is another way to multiply numbers on paper. In school I learned this method:

US Mulitplication

  39
 x25
-------
 195
+78 
------
 975

That works fine, but it requires you to know your multiplication table well, which I never did until . . . ok, I confess I used a calculator to multiply 39 x 5 and 39 x 2, so I still don't multiply very well.

But there's a method called Peasant Multiplication that only requires that you know how to double and halve numbers. With this method you put the two numbers you want to multiply at the top of two columns. Then, for the first column you halve the number over and over (discarding any fractions) until you get to one. For the second column you double it the same number of times as you were able to halve the first number. Next, strike out any rows where the number in the first column is even and add up the remaining numbers in the second column:

Peasant Multiplication

  39  X  25
  19     50
   9     100
   4     200
   2     400
   1     800
        -------
         975

This method is more common in European classrooms than in the US, but I like it, despite its disparaging title.