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Digital album version for Aussie coins


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Very well done, like your site too. Watched the video regarding decimal versus LSD.


When we were kids, brought up on duodecimal, we could perform mental arithmetic, an art form which has all but disappeared in this decimal age.



The number twelve, a highly composite number, is the smallest number with four non-trivial factors (2, 3, 4, 6), and the smallest to include as factors all four numbers (1 to 4) within the subitizing range. As a result of this increased factorability of the radix and its divisibility by a wide range of the most elemental numbers (whereas ten has only two non-trivial factors: 2 and 5, with neither 3 nor 4), duodecimal representations fit more easily than decimal ones into many common patterns, as evidenced by the higher regularity observable in the duodecimal multiplication table.


In other words, a shilling could be subdivided into ; 6d, 4d, 3d, 2d, 1d whereas 10c can only divide into 5c, 2c, 1c. I realize that with inflation a penny, tuppence, thru'penny bit, groat would not have much buying power now, but for centuries they were valuable coins in Great Britain. Also 5 X 2 shillings = 1/2 a pound, 4 X 2/6 = 1/2 a pound. 4 X 2 shillings = 8 shillings, 8 shillings X 2.5 = 1 pound...... etc.


The permutations, based on the duodecimal coinage seemed to make perfect sense and made mental arithmetic quite easy.


I am sure it was good training for the brain too.

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