Can You Work Out This Sum

[barney15c]

I tried using bomdas and came up with an answer but dont know if i did it right:

4x4+4x4+4-4x4

I make it 20 is that right if not can you tell me what it is and how you arrived at the answer - thanks

PS apparently 73% of people get it wrong

[Prudie]

There is a rule for doing this as several people have posted and the answer is 20.

[bibblebub]

272 using a stack-based approach

[Paulsy]

Where's factor 30 when you need him

[Fibonacci]

BIDMAS [ sometimes called BODMAS or even BEDMAS] is a Mnemonic to remind people of the order in which calculations with mixed operations should be worked out http://www.bbc.co.uk/bitesize/ks3/maths/number/order_operation/revision/2/

so even without brackets - there is an order in which to carry out the numerical calculations
Multiplications are worked out first
so 4 x 4 + 4 x 4 + 4 - 4 x 4
becomes 16 + 16 + 4 - 16
with only add and subtract then left you work out in the order you find them. starting from the left of the sum and working towards the right
16 + 16 = 32 , 32 + 4 = 36 and finally 36 - 16 = 20

[frugalfred]

Is 20 a Fibonacci Number?

[Paulsy]

68

[Fibonacci]

20 is not a number in the Fibonacci sequence but it is a tetrahedral number = 1 + 3 + 6 + 10

[barney15c]

Are we decided that the answer is 20 :)...i too dont think it matters there are no brackets, you follow the rules explicitly to boddas bidmas or whatever.

Why would i want to know the answer anyway? ...it was a question on Facebook , thanks guys for all your answers!

[factor-fiction]

20.

If it was algebra with a=4 and b=4 we'd write it as ab+ab+a-ab. That simplifies to ab+a.
Substituting in the values for a and b then gives 16+4=20

However, apart from when setting a question in a lesson on the order of operations, I would always encourage someone setting out a calculation involving numbers to use brackets since it's easy for the reader to slip up without brackets and many readers aren't aware of BIDMAS. I'm also aware that in those mental maths calculations in magazines- they ignore BIBMAS and expect you to just do the calculations in the order they appear