Define a negative number.

A negative number is a number less than zero, often represented with a minus sign (-).

Negative numbers are used to represent values that are below zero, such as temperatures below freezing, debts, or elevations below sea level. They are an essential part of the number line, which includes both positive and negative numbers, as well as zero. On the number line, negative numbers are located to the left of zero.

In mathematics, negative numbers follow specific rules for operations like addition, subtraction, multiplication, and division. For example, when you add a negative number to a positive number, you are essentially subtracting the absolute value of the negative number from the positive number. If you multiply two negative numbers, the result is a positive number, because the two negative signs cancel each other out.

Negative numbers are also crucial in solving equations and inequalities. For instance, if you have an equation like \( x + 3 = 1 \), you would subtract 3 from both sides to get \( x = -2 \). Understanding how to work with negative numbers is fundamental for more advanced topics in mathematics, such as algebra and calculus.

In real life, negative numbers can be seen in various contexts. For example, if you have £10 and you spend £15, you would have a debt of £5, which can be represented as -£5. Similarly, temperatures below zero degrees Celsius are negative, like -5°C.

By mastering negative numbers, you will be better equipped to handle a wide range of mathematical problems and real-world situations.