# Finding Negative Exponents(KS3, Year 7)

homesitemaparithmeticfinding a negative exponent
A power with a negative exponent is equal to the reciprocal of the power (1 over the power) with the exponent made positive. Imagine we have the number 2 with an exponent of -n. We put the whole power under 1 and remove the minus sign from the exponent. This is equal to 12n. This is a laws of exponents.

## Question

Use the law of exponents to find the power with the negative exponent below.

## 1

Write 1 on top of a fraction (called the numerator).

## 2

Write the power from the question on the bottom of the fraction (called the denominator).

## 3

Remove the minus sign from the exponent. In our example, the exponent of −2 becomes 2.
We have used the law of exponents to express the power with a negative exponent as a power with a positive exponent. As the final step, evaluate the power with the positive exponent.

## 4

Evaluate the power on the bottom of the fraction. In our example, evaluate 32.
32 = 3 × 3 = 9

We have found the negative exponent.

## Understanding Finding a Negative Exponent

Let us look at the rule for negative exponents:
• 2−n and 2n are powers.
• The bases of the powers are 2.
• The exponent of 2−n is −n and the exponent of 2n is n.
• The fraction 12n is the reciprocal of 2n.

## Lesson Slides

The slider below shows another real example of how to find negative exponents.

## What Is an Exponent?

An exponent tells you how many times a number or letter is multiplied by itself. An exponent is denoted by a raised number by the right hand side of the number (called the base) that is multiplied by itself. For example, 22 means that 2 is multiplied by itself 2 times:
22 = 2 × 2

## What Is a Reciprocal?

A reciprocal of a quantity (such as a letter or power) is 1 divided by the quantity.

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