Last 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:
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.
Well technically you didnt ask what it equaled so the answer is 7+(7÷7)+(7×7)-7 and there is no need to go any further
So Dustin.. what does the equation evaluate to?
a lack of brackets?
Does not need brackets. Use Order of Operations.
If you enter this on a calculator the answer is 0!
Hi Faye
Did you add your own brackets as I cannot get zero. Note adding brackets in the wrong location will change the equation.
Using Windows Calculator in Standard Mode: 7+7÷7+7×7-7 = 56 because calculated immediately left to right
7+7=14/7=2+7=9*7=63-7=56 This is incorrect.
Using Windows Calculator in Scientific Mode: 7+7÷7+7×7-7 = 50 due to order of operations
Using Search Engine: Both Google and Bing convert to 7+(7÷7)+(7×7)-7 = 50
Adding my own brackets in the wrong locations: (7+7)÷(7+7)×(7-7) = 14÷14×0 = 0, This is incorrect as Order of Operations says Multiplication and Division before Addition and Subtraction.
Regards
David
Unfortunately you too wrong
This actually means
(7+7) 14 14
_______ = ______ = ___ = undetermined
(7+7) × (7-7) (14)×(0) 0
Look up order of operations and don’t add brackets where there are none. Multiply and Divide before addition and subtraction.
This answer is 17.
Because 3-3×6+2=
3×6=18
18+2=20
20-3=17
You have posted this comment on the wrong article. And your maths is wrong.
3-3×6+2=
-3×6=-18 so 3-18+2=
-18+2=-16 so 3-16=
Answer 3-16=-13
or
-3×6=-18 so 3-18+2=
3-18=-15 so -15+2=
Answer -15+2=-13
To do the calculation the way you want to you need to change the sign because you have moved the 2 inside virtual parenthesis
3×6=18 so 3-18+2=
3-(18-2) = 3-(16)=-13
You CANNOT ignore the sign on the -18.
Subtraction is the same as adding a negative number so you can think of 3-3×6+2= as
3 + -3×6 + 2 = 3 + -18 + 2 = 3 + -16 or -15 + 2 or 5 – 18 = -13
Read this article for the full explanation: https://winthropdc.wordpress.com/2016/02/10/answer-only-for-genius-3-3-x-6-2/
David
What is ÷
It is the symbol for division.
I actually got the correct answer
7+7÷7+7×7-7
According to BODMAS ,I started with the division,then I multiply,then add,nd finally subtract my final answer, giving me XX [Edited answer out of comments]