What are Napier's Bones?
How do you multiply large numbers together?
1034 x 9
You may use horizontal partitioning
or a grid
or if you're super efficient you can do this
Well back in the late Tudor times
they used
bones.
Napier's Bones as they came to be called.
This is the 2 bone.
What do you notice about it?
This is the nine bone.
The way it works is this. Choose the bones that make the number you want to multiply.
Say you want to multiply 1034 x 9.
You can see we have chosen the 1, 0 , 3 and 4 bones.
Now look down the left hand side until you get to 9.
Now add diagonally - the tricky bit.
Starting from the right.
9306
Try the Interactive Version
You will need to refresh the page if you choose the wrong bone.
Amazingly it works.
You can also multiply by a two digit number,
you just have to adjust the place value for multipying by a ten although they didn't call it that in those days.
How would you do it today?
Click here for an answer
Make your own set of bones and challenge someone to work out a question or two.
You know how a Times table can be used for Division.
Do you think Napier's Bones could be used for division?
How about Decimals?
