How many liters are in a gallon? If the temperature is 33
degrees Celsius, what is it in degrees Fahrenheit?
If you know the answers, good for you! But if you can’t
remember, don’t feel too bad; most Americans can’t remember
either. That’s because the relationship between measurement
systems seems completely random. There’s no obvious reason why
there are 3.8 liters in one gallon, rather than, say, 3.9 or 4.2
liters. Similarly, there’s no obvious reason why water, which
boils at 100 degrees Celsius, requires 212 degrees on the
Fahrenheit scale.
Random facts are hard to remember. You can try to memorize
them the way school children do. Or, you can just estimate. You
can notice that four liters is a little more than a gallon, and
most of the time, that’s good enough. For example, in the
grocery store, it means that three liters of soda for $2 is a
better bargain than half a gallon at the same price. Similarly,
if you’re on holiday in France, and the radio reports that the
temperature on the Cote d’Azur is 35 degrees Celsius, don’t
worry about how to convert precisely to Fahrenheit. If you can
just remember that body temperature is about 37 degrees Celsius,
then you know that an air temperature of 35 degrees Celsius
means it’s going to be a hot day at the beach.
It isn’t just about weights and measures, either – the same
principle works for remembering dates. If have trouble
remembering whether your sisterinlaw’s birthday is October 12^{th}
or October 15^{th}, don’t sweat the details. Just
estimate. Remember that the big day falls in the same month as
Halloween, send your card in early October, and bask in the
approval when she calls to tell you your card was the first to
arrive.
 Copyright ©
2005 Memory Loss and the Brain 

