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Chapter overview
Learning goals
Learning Goals
Maths
Types of numbers
Number calculations
Fractions, decimals and percentages
Algebraic manipulation
Formulae and equations
Straight line graphs
Other graphs
Ratio
Proportion
Rates of change
Shapes
Properties of shapes
Lines and angles
Drawing shapes
Trigonometry
Probability
Maths
Summary
Negative numbers are numbers that are less than zero. It's possible to add, subtract, multiply and divide with them.
To add and subtract negative numbers, it is best done with a number line.
What is $-4+5$?
Start off at $-4$ on the number line, then move $5$ steps to the right.
[asset: number line]
Moving $5$ steps to the right ends up at $1$.
$\underline{-4+5=1}$
What is $10-(-5)$?
Subtracting a negative number is the same as adding a positive number. Therefore:
$10-(-5)=10+5=15$
$\underline{10-(-5)=15}$
To multiply and divide negative numbers, multiply them as if they were positive numbers. If the two numbers have different signs (so if one is positive and the other is negative), then add a negative symbol to the answer.
What is $-5\times-7$?
Multiply the two numbers together as if they were both positive:
$5\times7=35$
Since both numbers have the same sign (they are both negative), there is no need to change the sign of the answer.
$\underline{-5\times-7=35}$
What is $100\div-10$?
Divide the two numbers as if they were both positive:
$100\div10=10$
The numbers have opposing signs - one is negative and one is positive. Hence, the answer will be negative.
$\underline{100\div-10=-10}$
Negative numbers are numbers that are less than zero. It's possible to add, subtract, multiply and divide with them.
To add and subtract negative numbers, it is best done with a number line.
What is $-4+5$?
Start off at $-4$ on the number line, then move $5$ steps to the right.
[asset: number line]
Moving $5$ steps to the right ends up at $1$.
$\underline{-4+5=1}$
What is $10-(-5)$?
Subtracting a negative number is the same as adding a positive number. Therefore:
$10-(-5)=10+5=15$
$\underline{10-(-5)=15}$
To multiply and divide negative numbers, multiply them as if they were positive numbers. If the two numbers have different signs (so if one is positive and the other is negative), then add a negative symbol to the answer.
What is $-5\times-7$?
Multiply the two numbers together as if they were both positive:
$5\times7=35$
Since both numbers have the same sign (they are both negative), there is no need to change the sign of the answer.
$\underline{-5\times-7=35}$
What is $100\div-10$?
Divide the two numbers as if they were both positive:
$100\div10=10$
The numbers have opposing signs - one is negative and one is positive. Hence, the answer will be negative.
$\underline{100\div-10=-10}$
Negative numbers
FAQs
Question: How do you multiply and divide negative numbers?
Answer: Multiply/divide them as if they were positive, then add a negative symbol if the two numbers had different signs.
Question: How do you add and subtract negative numbers?
Answer: Use a number line. Move to the right if adding a positive number or subtracting a negative number. Move to the left is subtracting a positive number or adding a negative number.
Question: What is a negative number?
Answer: A negative number is a number that is less than zero.
Theory
Exercises
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