The story of the equal sign- what it means and how to use it

The equal sign as we know it today (=) wasn't invented by mathematicians until 1557, and even then, it took a while for mathematicians everywhere to start using it. Nonentheless, the concept that it represents - equality - has been used and studied for thousands of years.

The Merriam-Webster online dictionary defines equal to mean "of the same measure, quantity, amount, or number as another". So if I say "Jen is equal in height to Chris" this means that I, Jen, am the same height as Chris.

You'll notice that this statement about height can be true or false. It might be true that I'm the same height as Chris, or it might be false. In this case, there's a fact of the matter that we can determine by measuring my height and Chris' height.

The concept of equality works the same way in mathematics. The equal sign (=) can be translated in words as 'equals'.

This means that the mathematical equation

3 = 4

can be written out as

"The number three equals the number four."

In this case, the statement above is FALSE, because only the number four equals the number four.

Similarly, the mathematical equation

2 = 2

can be written out as

"Two equals two."

This is a TRUE statement because two does equal two.

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Copyright Jen Schellinck, 2006