From JohnNapier.com:
John Napier's rods (1617) are one of his most important contributions to the world of mathematics and represents one of the most revolutionary developments in calculation devices since the abacus. The rods were basically multiplication tables inscribed on sticks of wood or bone. Each rod is inscribed with a multiplication table of a number from 0 to 9. The rod to the extreme left, with numbers from 0 to 9 is used as an index for quick reference.
You just add the numbers "on the diagonal" to multiply, so in this case 2 x 6497 = 12994, for example.
What diagonal?
Posted by: bsprowl | 04/25/2008 at 08:52 PM
2 x 6497 = 12994 =
1
2+0=2
8+1=9
8+1=9
4
Posted by: Tom McMahon | 04/26/2008 at 09:24 AM
Forgive me for enjoying the beauty of your body and soul；
Forgive me for wanting to be with you when I grow old!
Posted by: cheap louboutin | 11/09/2010 at 02:32 AM
You just add the numbers "on the diagonal" to multiply, so in this case 2 x 6497 = 12994, for example....
Posted by: Herve leger | 05/12/2011 at 09:01 PM
Forgive me for enjoying the beauty of your body and soul；
Forgive me for wanting to be with you when I grow old!
Posted by: authentic air jordan shoes | 06/12/2011 at 10:15 PM
Forgive me for enjoying the beauty of your body and soul；
Forgive me for wanting to be with you when I grow old!
Posted by: eergo infant carrier | 10/06/2011 at 02:31 AM