Talk:Promptuary

Napier's description of the promptuary specified 100 numbers cards and 100 mask cards.

This example is said to have 200 mask cards - I don't know what the extra 100 are for.

This example is said to be able to handle 100-digit numbers. This seems unlikely - Napier's promptuary could only handle 10-digit numbers. I'd need to see more details of the Spanish device to see is the claim true.

Gnomon (talk) 15:02, 12 March 2020 (UTC)[reply]

The only way this makes sense is if the number strips have 20 copies of the multiplication table, instead of the 10 described by Napier in his book. In this case, there would be 100 number strips and 200 mask strips needed, and the device could multiply a 10-digit by a 20-digit number rather than a 100-digit number by a 200-digit number.

I'm changing the article to say that.

87.198.212.130 (talk) 16:06, 12 March 2020 (UTC)[reply]

Still not happy with that. The picture on the Spanish wikipedia suggests this device can handle a 10-digit number times another 10-digit number. So why are there 200 mask cards? Gnomon (talk) 22:39, 21 March 2020 (UTC)[reply]

I've added a huge section based on Napier's book explaining the device in detail and how it is used. Gnomon (talk) 13:04, 17 April 2020 (UTC)[reply]