Checking Maths Answers

At the end of any kind of test, it’s important to check your work. It’s sometimes called ‘sanity checking’, which just means making sure your answers aren’t crazy!

Checking in English is relatively easy because you just have to look out for mistakes with spelling, capital letters, punctuation or other grammar. However, checking in Maths is much harder because there are so many different types of questions. So what’s the answer?

Well, you could always repeat your working for every single question, but that means any test would take twice as long! You don’t have time to do that, so there must be another way. In my experience, you should learn a few different ways of checking that are simple and quick to use.

If you have a mental checklist to go through, it should help you avoid silly mistakes.

Instructions

Have you read all the instructions on the front page? They might contain important guidelines about how to do the exam. For example, you might be told to show your working for every sum—even if there’s no mark scheme, which would usually mean there’s just one mark for a correct answer.

Units

The easiest and quickest way to check your answer is to make sure you’ve included the units! It may be true that 25 x £1.60 is £40, but you won’t get the mark unless you put in the pound sign…

Numbers

Have you copied down the numbers correctly in your sums? You’ll never get the right answer if you’re asking the wrong question…!

Addition

You can use the column method for as many numbers as you like. If you try to add 8, 7 and 5 one by one, there’s a danger you’ll end up saying 8 + 7 = 15 + 5 = 20, which is wrong!

Multiplication

There are a couple of ways of checking a multiplication sum.

Last Digits

  1. Multiply the last digits of both numbers together.
  2. Make sure the last digit of that number and your answer are the same.
  • Eg 3,792 x 26 must end with a 2 because 2 x 6 = 12, and 12 ends with a 2

Rounding

  1. Round both numbers to one (or two) significant figures.
  2. Multiply them together.
  3. Make sure the number you get and your answer are roughly the same size.
  • Eg 3,792 x 26 must be roughly 120,000 because 4,000 x 30 = 120,000 

     

     

     

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