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A1093600 - Napier's Bones - a 17th-Century Calculation Aid

Post 1

Gnomon - time to move on

Entry: Napier's Bones - a 17th-Century Calculation Aid - A1093600
Author: Gnomon - time to move on - U151503

If this is thought to be suitable I can do better diagrams.


A1093600 - Napier's Bones - a 17th-Century Calculation Aid

Post 2

SashaQ - happysad

Very interesting - thank you for writing this up for the Guide smiley - biggrin

Just one typo: "the left and right sides of the squares should not marked on the rods. " - should not be marked on the rods

"This arrangement ensures that a set of 10 rods can multiply any number of up to 4 digits in length and also many bigger numbers, as long as they don't have too many repeated digits." - I see that 10 4-sided rods can work with numbers less than 11,111, as there will be no more than 4 repeated digits. Perhaps that sentence could be made clearer about what 'bigger' and 'too many' mean.

The tables and photo of your Napier's Bones are very helpful, so I could visualise how it works in the examples smiley - ok


A1093600 - Napier's Bones - a 17th-Century Calculation Aid

Post 3

Gnomon - time to move on

Thanks for your reply, Sasha.

I've fixed the typo.

It's not easy to specify exactly which long numbers can be represented. If a number has four 1s, for example, it can't also have four 2's because one of the 2s has already been used in the rods used for the four 1s. Rather than getting into an exact and boring specification, I had hoped that "not too many" would be enough information for most people.

Glad you like the diagrams.

smiley - smiley


A1093600 - Napier's Bones - a 17th-Century Calculation Aid

Post 4

SashaQ - happysad

smiley - ok

Aha - I was thinking about numbers with only five digits, but there will be some 10 digit numbers that 10 rods can work with, I see now smiley - ok


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