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A power is a way of writing repeated multiplication of the same number. They help express large and small numbers efficiently. In general, a power is written as:
$$ a^n $$
where:
For example:
$$ 3^4 = 3 \times 3 \times 3 \times 3 $$
Understanding the following properties will help you develop a strong grasp of exponents and indices.
$$ \text{For example, } 3^4 \neq 4^3 $$
$$ a^1 = a $$
$$ a^0 = 1 \quad \text{where } a \neq 0 $$
Two of the most common powers are squares (index 2) and cubes (index 3).
Square Numbers:
$$ n^2 = n \times n $$
$$ 1^2 = 1, \quad 2^2 = 4, \quad 3^2 = 9, \quad 4^2 = 16, \quad 5^2 = 25, \quad 6^2 = 36 $$
Cube Numbers:
$$ n^3 = n \times n \times n $$
$$ 1^3 = 1, \quad 2^3 = 8, \quad 3^3 = 27, \quad 4^3 = 64, \quad 5^3 = 125 $$
Recognizing square and cube numbers helps you simplify expressions and solve equations more easily.
When multiplying the same number multiple times, you can use exponents (indices) to write the expression in a simplified form.
For example:
$$ 4 \times 3 \times 3 \times 4 \times 4 $$
We can group the same factors using the commutative and associative laws:
$$ (4 \times 4 \times 4) \times (3 \times 3) $$
Since each base is repeated, we can write it using exponents:
$$ 4^3 \times 3^2 $$
By using exponents for repeated multiplication, you make expressions easier to read, write, and work with.
In BIDMAS (Brackets, Indices, Division, Multiplication, Addition, Subtraction),
indices (exponents) are calculated after brackets but before all basic operations.
Example 1: Brackets Before Indices
When an expression has brackets, evaluate the brackets first:
$$ (2 \times 5)^2 $$
$$ (10)^2 $$
$$ 100 $$
Example 2: Indices Before Multiplication
If there are no brackets around the multiplication, apply the exponent first:
$$ 2 \times 5^2 $$
$$ 2 \times 25 $$
$$ 50 $$
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