Napier's Bones

The table is split up into the nine columns. Here is how they're used:

For example, let's calculate 32 x 7 .

Lay out the two strips showing 3 and 2 at the top like this:

To multiply this number by 7, add the numbers along the diagonals of the seventh line, starting at the right:

So the answer is 224 .

Here's another example, this time we are multiplying 746 by 6. Click on Napier to start the demo.