Equals sign facts for kids

The equal sign, also called the equals sign or just "=", is a math symbol. It shows that two things are exactly the same in value or amount. It looks like two parallel horizontal lines, one above the other. You place the equals sign between the things you are saying are equal. For example, in "2 + 2 = 4", the equal sign shows that "2 + 2" has the same value as "4".

What the Equal Sign Means

The equal sign is super important in math. It helps us write down equations and solve problems. When you see an equal sign, it means that whatever is on one side of it has the exact same value as whatever is on the other side. Think of it like a balanced scale: both sides must weigh the same.

The equal sign was first used by a Welsh mathematician named Robert Recorde in 1557. He wrote a book called The Whetstone of Witte. He chose two parallel lines because, as he said, "no two things can be more equal" than them. Before this, people used words like "is equal to" which took up a lot of space.

Symbols That Are Not Equal

Sometimes, things are not equal. For this, we use a special symbol:

• "≠" (a slashed equal sign): This means "is not equal to". For example, 5 ≠ 6 means that 5 is not the same as 6.

Symbols That Are About Equal

There are also symbols to show when things are close to being equal, but not exactly. These are called "approximately equal" or "similar to" symbols:

• "≈" (two tildes or wavy lines): This often means "approximately equal". You might use it when you round a number. For example, if you round 3.14159 to two decimal places, you could say π ≈ 3.14.
• "≡" (three lines): This symbol means "is equivalent to" or "is identical to". It's used when two things are always the same, no matter what values are put in.

Each of these symbols helps mathematicians explain relationships between numbers and ideas.

Related pages

• Equality (mathematics)
• List of mathematical symbols

Images for kids

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  The first use of an equal sign, equivalent to 14x+15=71 in modern notation. From The Whetstone of Witte (1557) by Robert Recorde.

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  Recorde's introduction of "="

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  The signature of Santos-Dumont, showing a double hyphen that looks like an equal sign.

See also

In Spanish: Signo igual para niños