Napier's Bones

Napier's Bones

This is really incredible!

This is a Fun and Easy Way To Multiply Big Numbers.

Ths is how it works

Let's say we want to Multiply:

3579 x 4

Lay out the bones that have the top numbers 3, 5, 7, and 9. (See picture above)

Starting from the right side, in the 4th row, add the two numbers in each diagonal 

of that row, and then write its sum underneath that column. (See picture above)

You can see the 4th row highlighted in picture.

If you get a two-digit sum, you will need to write down the ones digit, 

and then carry the other digit over to the next diagonal to the left to be added with it.  

See picture below

So in the picture above is just the one row.

Notice the the diagonal with the 8 and the 3. Since 8 + 3 = 11, 

we wrote the 1 underneath, and carried the other 1 to the diagonal to its left. 

And that is the answer

Very cool!!

Click here to download the pdf