KS3 Maths Using VAT Revision | KS3 Maths Resources

What you need to know

Things to remember:

• To find 20% of a number we divide by 5.
• To find how much something is after VAT, we divide by 5 and add this new amount to the originally amount.
• To find the original amount of something after VAT, we divide by 6 and multiply by 5.

VAT is a tax of 20% that is added to most goods. This topic should be pretty nice, because all we really need to do is find 20% of something!

Hint: Remember, to find 20% of a whole (100%), we divide by 5.

What is 20% of 65?

$$65\div5=13$$

20% of 65 is 13

A pair of shoes cost £65 before VAT. How much will the VAT be?

$$\pounds65\div5=\pounds13$$

The VAT on the £65 shoes is £13

There are three types of VAT question:

• Finding the VAT of an item
• Finding how much an item costs after adding the VAT.
• Finding out what the the original cost of an item was before VAT was added.

The meal costs £40 before VAT. What is the value of VAT that will be added?

$$40\div5=18$$

The VAT of the meal will be £8.

A car costs £8000 before VAT. What will be the price of car after VAT is added?

Step 1: Find the value of the VAT

$$\pounds8000\div5=\pounds1600$$

Step 2: Add the VAT (the value in Step 1) to the original amount.

$\pounds8000+\pounds1600=\pounds9600$

The value of car after VAT is £9600

A computer costs £750 after VAT. What was the cost of computer before the VAT was added?

We need to think about the value of the computer in two ways:

• The value before VAT, the original amount.
• The value after the VAT is added.

If we think about the original value as 100% then we have added 20% to get the value after VAT.

Original amount = 100%

Amount after VAT = 100%+20%=120%

So, we are actually trying to get from 120% to 100%, which we can do by subtracting 20%. We need to be careful here, 20% of £750 will be more than 20% of the original amount, so we will do this in slightly different justify.

Step 1: Divide by 6 to get 20%.

$$120\% \div6=20\%$$

$$\pounds750 \div6=\pounds125$$

We now have two different steps to choose from to find the original 100%.

Step 2a: Subtract the value in Step 1 from the original amount.

$$120\%-20\%=100\%$$

$$\pounds750-\pounds125=\pounds625$$

Step 2b: Multiply the value in Step 1 by 5.

$$20\%\times5=100\%$$

$$\pounds25\times5=\pounds625$$

So, as we can see, it doesn’t matter which method we choose, we will get the same answer.

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Example Questions

Step 1: Find the value of the VAT

$$\pounds75\div5=\pounds15$$

Step 2: Add the VAT (the value in Step 1) to the original amount.

$\pounds75+\pounds15=\pounds90$

The value of jeans after VAT is £90

Step 1: Divide by 5 to get 20%.

$$\pounds45 \div5=\pounds9$$

Step 2a: Subtract the value in Step 1 from the original amount.

$$\pounds45-\pounds9=\pounds36$$

Step 2b: Multiply the value in Step 1 by 4.

$$\pounds9\times4=\pounds36$$

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