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The four operations

The four arithmetic operations are addition, subtraction, multiplication and division.

Addition ($$+$$) gives the sum of two numbers.

Subtraction ($$-$$) gives the difference. Order matters.

$$$\Tblue{10}-\Tgreen{3}=7,\qquad \Tgreen{3}-\Tblue{10}=-7 = -(\Tblue{10}-\Tgreen{3}).$$$

Addition and subtraction are inverse operations. In other words, adding a number $$B$$ to a number $$A$$ and then subtracting the number $$B$$ from the sum will yield the original number $$A$$.

$$$ (\Tgreen{18} - \Tblue{15}) + \Tblue{15} = 3 + \Tblue{15} = \Tgreen{18}.$$$
Addition and subtraction can be visualised using a number line.
Addition and subtraction can be visualised using a number line.

Multiplication ($$\times$$) gives the product of two numbers.

$$$\Tgreen{5} \times \Tblue{3} = \Tblue{3} \times \Tgreen{5} = 15.$$$

Division ($$\div$$) gives the quotient of two numbers. Order matters.

$$$\Tblue{24} \div \Tgreen{6} = 4,\qquad\displaystyle\Tgreen{6} \div \Tblue{24} = \frac{1}{4} = \frac{1}{\Tblue{24} \div \Tgreen{6}}.$$$

It is impossible to divide by zero.

Multiplication and division are inverse operations. In other words, multiplying a number $$A$$ by another number $$B$$ and then dividing the product by the number $$B$$ will yield the original number $$A$$.

$$$ (\Tblue{18}\div \Tgreen{6}) \times \Tgreen{6} = 3\times \Tgreen{6} = \Tblue{18}. $$$