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Where did they come from? (or 'cutting a long story short')
A symbol is a simple shape or simple picture that stands for a more
complicated idea. Mathematicians like to use symbols because, with
just a few squiggles and shapes, they can tell a rather long
mathematical story.
For example:
64 people arrived on
time and sat down in the theatre. 23 more people came in late and 5
people left just after the play started. If we combine the 64 and
the 23 we get 87 people. Take off the 5 that left and that leaves
82 people still watching the play .
If we use symbols this could be just written as
64 + 23 - 5 = 87 - 5 = 82
Someone, often long ago, invented these symbols and other people
started using them. The
plus sign
+ seems to have started as a quick way of writing the Latin
word et, which means 'and' as long ago as the year 1417.
Here is a picture of some of the earliest uses of
plus + and
minus - symbols in a printed book
(1526).
It is thought the equal sign = was invented by Robert Recorde. In
1557, "I will sette as I doe often in woorke use, a paire of
parralles, or Gemowe lines of one lengthe, thus ==, bicause noe 2
thynges can be moare equalle."