Decimalisation

I think I’ve worked out where the British capacity for mental arithmetic met it’s demise. It wasn't, as you might think, when the pocket calculator came along. Nor was it when they stopped teaching real maths in school because it was too hard. No, the rot set in back in 1971 when we converted our currency to decimal.

Before then we had a wonderful system based on pounds, shillings, pennies and ha'pennies. There were two ha'pennies in a penny. Twelve pennies in a shilling. Twenty shillings in a pound. Or, if you wish, two hundred and forty pennies in a pound. Oh, and you also had a guinea which was twenty one shillings. Expensive items like cars and fridges and fancy clothes were often priced in guineas. Some places still use guineas today but it's somehow lost its romanticism now as it's £1.05. You also had weird coins like the half crown which was two shillings and sixpence and a thrupenny bit which was three pence. I'm too young to remember farthings which were worth a quarter of a penny.

To work in this currency, you had to be able to add up in base 12 and base 20. If you bought two items, one costing seven shillings and sixpence and the other costing four shillings and eightpence it would add up to twelve shillings and two pence (or tuppence). This was expressed in writing as 7/6 + 4/8 = 12/2. Verbally, 7/6 was expressed simply as "seven and six".

When you reached twenty shillings (20/-), you got a pound. But that didn't neccesarily mean that you expressed the pound in notation. Some people just kept adding up the shillings so one pound seventeen shillings and sixpence would often be written as 37/6 but could also be £1/17/6.

Added to this, certain denominations had nicknames, so a shilling was usually called a bob. A two shilling coin was called a florin. A sixpence coin was called a tanner. A quid was, and still is, a pound.

I was eight years old when they got rid of this system yet I can remember being able to easily add up sums of money using this system. It came completely naturally to me as it was ingrained in the culture, like language. Lots of people of my generation and of course my parent's generation can do the same but present this system to a teenager today and they're bewildered.

When we converted to a decimal currency, all the old coins were retained and new ones introduced alongside. So an old sixpence was now worth 2.5 new pence. An old shilling was worth 5 new pence. A half crown was worth 12.5 new pence. Working with two sets of coins in my small pockets was easy as well. This was money - it was important you didn't make mistakes so you learnt it fast!

Mental arithmetic was and still is easy. It was at least another five years before even the simplest pocket calculator was available and these were too expensive for most people to afford anyway. I remember the anger expressed by many people who said that introducing a decimal system would be too confusing. It would simply be a way for shopkeepers and the government to put up prices without people noticing.

If you want a numerate society, I suggest reintroducing the above system. A fiendishly complex currency is a great way of learning how to add up quickly in your head.

Happy days.