This page has been put together to help you practise and revisit some of the brilliant skills you’ve learned all through primary school.

It’s a great way to boost your confidence in Maths and get you ready for the exciting next step into Year 8!

Finding mistakes in a maths problem is a top skill to have and it's a great way to get better at checking your own work.

In this guide, you'll learn how to spot common errors in calculations, like mistakes with place value or decimal points.

We'll also look at how to explain what went wrong and how to correct it!

A very common question in a maths test is the error spotting question.

You will be shown a calculation or a word problem that has a mistake.

Your job is to be a detective: find the mistake, explain what the pupil did wrong using clear mathematical terms, and show the correct working.

Let's look at a classic example in column subtraction.

The Problem: Anna was asked to solve £500 - £135.

Here is her working:

Her final answer was £435. Can you spot the mistake?

The Explanation: Anna's mistake happened in the units column. She tried to calculate 0 - 5 and wrote 5. She forgot to exchange (or 'borrow') from the tens and hundreds columns. Because the tens column was also a zero, she needed to exchange from the 5 in the hundreds column, all the way across.

By exchanging, the calculation becomes:

Units: 10 - 5 = 5

Tens: 9 - 3 = 6

Hundreds: 4 - 1 = 3

The correct answer is £365.

Another very common error is with place value, especially when decimal points are involved. This is a key part of the KS2 Number curriculum.

The golden rule is: line up the decimal points!

The Problem: Éamonn tried to add 14.5 + 3.95. Here's his setup:

The Explanation: Éamonn's mistake was in the set-up. He lined up the numbers on the right-hand side, instead of lining up the decimal points. This means he added the 5 tenths (50p) from 14.5 to the 5 hundredths (5p) from 3.95, which is incorrect.

The Correction: To fix this, you must line up the decimal points. It helps to add a placeholder zero to 14.5 to make it 14.50.

This shows the correct answer is 18.45. Always check the set-up!

Sometimes, a calculation is done correctly, but the method itself is wrong.

The Problem: A question asks: 'Find 25% of 80'. Charlie writes: 'To find 25%, I divided 80 by 25. The answer is 3.2.'

The Explanation: Charlie's calculation (80 ÷ 25 = 3.2) is correct, but his method is wrong. He has confused '25%' with 'divide by 25'.

The Correction: To find 25% of a number, you are finding a quarter (1/4). The correct method is to divide the number by 4.

Correct Working: 80 ÷ 4 = 20.

So, 25% of 80 is 20.

This type of error shows why you must read the question carefully and understand what it is asking you to do

Well done, error spotter! You now know how to check calculations for common mistakes.

You can spot errors in exchanging (subtraction), place value (decimals), and method (percentages).

Think about these questions to stretch your thinking and sharpen your skills!

• What is the most common mistake pupils make when calculating £1000 - £253? (Hint: Think about all the zeros!)

• A pupil says, 'To find 50% of 90, I divide by 50.' Explain their mistake and describe the correct method.

• Look at this sum: 7.2 x 100 = 7,200. Is this correct? Explain the mistake in terms of place value or 'moving the decimal point'.

Have a chat about your answers with a parent, teacher or your class.