31 years ago yesterday I finished my A levels; 31 years ago yesterday I left my Sixth Form College to embark upon a very roller-coaster life.

What’s the significance of 31years? None really. But then, why should 25 years or 50 years be more significant than 31 years or 56 years? Why do certain numbers seem to have a hold over us?

100 seems to be a powerful number. I know that it’s because it requires a third digit, but in the overall scheme of things how important is it? Does a cricket player who is out for 100 contribute substantially more to his team’s score than one who is out for 99? The media and the record books will note that he reached a century; out for 99 and he will be deemed to have in some way failed.

When someone reaches their 100th birthday a great fuss is made, but how often does anyone ask whether there has been life in the person’s years as well as years in the person’s life? I once knew a woman who eventually died in her 109th year. During the whole time I knew her she was bitter and nasty towards both the staff and the other residents of the home in which she lived, I was told by a local doctor who had known her since she was 80 that she had always been bad tempered and aggressive. Yet because she had reached three figures there was a kind of awe surrounding her.

100 holds us in thrall – and because it’s so important, fractions of 100 and multiples of 100 are regarded with great importance – tens, twenty-fives, fifties, seventy-fives, centuries, thousands. Certain numbers are invested with far greater importance than others, nearly all of them connected with the decimal system.

Decimals didn’t always have the same hold on us. The old money system didn’t follow decimals – four farthings in a penny, twelve pennies in shilling, twenty shillings in a pound, 21 shillings in a guinea. The old weight system didn’t follow decimals – sixteen drams in an ounce;  sixteen ounces in a pound; fourteen pounds in a stone; eight stones in a hundredweight; twenty hundredweights in a ton.

Decimals never played a big part in sport – look at the scoring in rugby, or Gaelic games, or even at soccer league tables – there is no fixation with hundreds, tens or tenths.

Why do zeros matter so much?  It’s not as though they have been around for so long; the Romans managed an entire civilisation without having any noughts.

Reaching the age of 50 this year, the number will be studiously avoided, it has no more significance than 51, 49 or 19.