Sign (mathematics) facts for kids
In mathematics, the word sign tells us if a number is positive or negative. Every real number that isn't zero has a sign. For example, 5 is positive, and -5 is negative. The number zero itself doesn't have a sign; it's neither positive nor negative.
When you see a number without a plus or minus sign, it's usually a positive number. For example, 7 means positive 7. If a number is negative, it will always have a minus sign (like -7) in front of it.
Sometimes, the word "sign" can also mean a mathematical symbol, like the plus sign (+), the minus sign (-), or the multiplication sign (×).
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What is the Sign of a Number?
A real number is positive if it's bigger than zero. It's negative if it's smaller than zero. This idea of being positive or negative is called the sign of the number. Remember, zero doesn't have a sign.
In arithmetic, we often use a plus or minus symbol to show a number's sign.
- For example, +3 means a positive 3.
- −3 means a negative 3.
If there's no plus or minus sign, we usually assume the number is positive. So, 5 is the same as +5.
Absolute Value and Signs
The absolute value of a number tells us its distance from zero. It always makes the number positive.
- For example, the absolute value of -3 is 3.
- The absolute value of 3 is also 3.
We write this using vertical bars:
- |−3| = 3
- |3| = 3
The absolute value function changes any non-zero number to its positive version.
Why Zero Has No Sign
The number zero is special because it is neither positive nor negative. Because of this, zero doesn't have a sign. In math, +0 and −0 both mean the exact same number, which is 0.
Related Topics
See also
In Spanish: Signo (matemáticas) para niños
