## What you need to know

**Things to remember:**

- An exponent, or power, tells us how many times we multiply a number by itself.

*What is the value of x if 3^x=81?*

Remember, an exponent is telling us that we multiply a number by itself a certain number of times. So, this question is asking us to see how many times we have to multiply 3 by itself to make 81. The easiest way to this is to just build it up.

x=1 3^1=3

x=2 3^2=3\times3=9

x=3 3^3=3\times3\times3=9\times3=27

x=4 3^4=3\times3\times3\times3=9\times3\times=27\times3=81

So, we can see that x=4!

3^4=81

## KS3 Maths Revision Cards

(77 Reviews) £8.99## Example Questions

**Question 1:** What is the value of x if 4^x=16?

x=1 4^1=4

x=2 4^2=4\times4=16

So, we can see that x=4!

4^2=16

**Question 2:** What is the value of x if 5^x=625?

x=1 5^1=4

x=2 5^2=5\times5=25

x=3 5^3=5\times5\times5=25\times5=125

x=45^4=5\times5\times5\times5=25\times5\times5=125\times5=625

So, we can see that x=4!

5^4=625

## KS3 Maths Revision Cards

(77 Reviews) £8.99- All of the major KS2 Maths SATs topics covered
- Practice questions and answers on every topic

- Detailed model solutions for every question
- Suitable for students of all abilities.