Answer: What is the answer? 7 + 7 ÷ 7 + 7 x 7 – 7


David Meego - Click for blog homepageLast week I posted a second mathematical challenge, and today I will go through the answer.

If you have not answered the poll on the second challenge, please go and do that now:

So here is the question again:

Maths_Question_2

And here is the answer: 50 7 + 7 / 7 + 7 x 7 – 7

Did you get it right? If not, here are the steps.

Remember your order of operations using your favourite mnemonic: BIMDAS, PEDMAS, My Dear Aunt Sally, etc. They all tell you that Multiplication and Division must be done at the same time, but before Addition and Subtraction. Then Addition and Subtraction can be done be at the same time.

i.e. My Dear Aunt Sally (MDAS) is actually the same as Dear My Sally Aunt (DMSA).

After the order of operations is handled, just calculate from left to right. So….

  • 7 + 7 ÷ 7 + 7 x 7 – 7

Do Multiplication and Division first.

  • 7 + 7 ÷ 7 + 7 x 7 – 7
  • 7 + 1 + 49 – 7

Then finish with Addition and Subtraction (from left to right).

  • 7 + 1 + 49 – 7
  • 8 + 49 – 7
  • 57 – 7
  • 50

You could also simplify the equation and cancel out the positive 7 and negative 7.

  • 7 + 1 + 49 – 7
  • 1 + 49
  • 50

Please note that if you type this into a simple calculator and so ignore the order of operations and just calculate each operation individually from left to right, you will get a different but incorrect answer.

  • 7 + 7 ÷ 7 + 7 x 7 – 7
  • 14 ÷ 7 + 7 x 7 – 7
  • 2 + 7 x 7 – 7
  • 9 x 7 – 7
  • 63 – 7
  • 56, but this is still wrong as you must multiply and divide first.

It was good to see that most people got this second challenge correct.

Hopefully, that should end the maths lessons for a while. 🙂

David

This article was originally posted on http://www.winthropdc.com/blog.

Advertisements

3 thoughts on “Answer: What is the answer? 7 + 7 ÷ 7 + 7 x 7 – 7

Please post feedback or comments

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s