THE POPULAR SCIENCE MONTHLY.
|Process 1.||Process 2.|
|The commentator considers this method as difficult, and not to be learned by dull scholars without instruction.|
Example 2. Multiply 15 by 12.
15 = 4 + 5 + 6. 12 = 2 + 4 + 6.
Example 3. Multiply 30 by 46.
Here is a larger example worked by the cross-method:
Example 4. Multiply 456 by 456.
|To indicate the successive steps the linking-lines are numbered, so as to show the groups in which the products are to be taken for addition.|
|Let the products be found and properly grouped and 456 added mentally, and one will better appreciate how much 456 depend upon mere mechanism in our own mental operations.|