Lately there has been a maths question on Facebook: 1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+1+1x0 =?
My husband says the answer is 4, according to what he learned at school: BODMAS. Standing for, in that order: Brackets, Of, Division, Multiplication, Adding, Subtraction.
The options for answering are 0, 14, 16 or 17. The answer '4' is not even an option. Is he wrong?

Yes. Multiply anything by 0, and the answer is 0.

But multiplication comes before addition, so only the last 1 becomes 0.

No, multiplication does not come before addition, it is done in the order it is written. If there are ( ) around certain parts of the question, then those are done separate.

If the one part was (1X0) then the remainder of the 1's would be added in which case it would be 16.

Annemieke and her husband are correct, at least about the order of operations (http://en.wikipedia.org/wiki/Order_of_operations). Given that, however, I fail to see how you could possibly come up with 4 as an answer!

By my count, unless the minus sign in front of one of those 1's is a typo, the answer is 14. If it was a typo, and it was supposed to be a plus, then the answer is 16.

Yep - 14 it is. I saw this same guestion on Facebook, and a lot of people are missing that little minus sign, and so are coming up with 16. Some people make the mistake of thinking that the "times 0" at the end applies to the sum of everything before, but that's incorrect (sorry Fr_Chuck).

And it's so disappointing to see so many people get the false answer... :(

It just dawned on me why the OP's husband thinks the answer is 4. If he does all the addition BEFORE the subtraction, I can see where he would get 10 - 6 = 4.

However, it's not true that addition comes before subtraction. Addition and subtraction are equal in the order of operations. Neither takes precedence over the other. Subtraction is nothing more than addition with negative numbers.

The same relationship holds true, by the way, between multiplication and division. Neither takes precedence over the other. They are just two manifestations of the same thing (division is the same as multiplication by the reciprocal).

By the way, Jerry, I agree. I can understand missing the minus sign; it's buried among all those plus signs. But order of operations is pretty fundamental.

Given most of what I see on Facebook, I'd be surprised if more than about a quarter of the people get it right, sadly. By the way, is that you standing in on the beach with the water behind you? Glad to finally have a face to put with the name.

Annemieke, either your husband is totally right, or I'm crazy as well! Here's how I would do it:

Step 1: Multiply
1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+(1 x 0)
=
1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+1+0

Step 2: Add
(1+1+1+1+1+1+1+1+1+1)-(1+1+1+1+1+1+0)
=
10 - 6

Step 3: Subtract
10 - 6 = 4

Annemieke, either your husband is totally right, or I'm crazy as well! Here's how I would do it:

Step 1: Multiply
1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+(1 x 0)
=
1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+1+0

You're crazy as well since you multiplied 1 by 0 and got 1+0...


Step 2: Add
(1+1+1+1+1+1+1+1+1+1)-(1+1+1+1+1+1+0)
=
10 - 6

When there are no brackets, you evaluate from left to right, DO NOT INTRODUCE YOUR OWN BRACKETS UNLESS YOU KNOW WHAT YOU'RE DOING.


Step 3: Subtract
10 - 6 = 4

Already many mistakes up there... so...

Ok, obviously I typed a 1 too many there. But the logic of what I'm doing is totally clear: you don't need brackets in just applying the right order.

No, your logic is totally clear but it's also totally wrong.

Ok, obviously I typed a 1 too many there. But the logic of what I'm doing is totally clear: you don't need brackets in just applying the right order.

As Unknown said, the order you applied is NOT right. Your logic is definitely clear (thanks to the parentheses you added), but addition does NOT come before subtraction. They are equal in order of operations; therefore, in the absence of parentheses, addition and subtraction take place from left to right. You skipped ahead, did all the addition on the right, then came back to the minus sign where you left off. That's not mathematically legal.

Who ever came up with this is brilliant. I am amazed how virale it has gone. I just can't stop laughing.
Denary... lol.

It's a trick question. It doesn't say what base system to use so the answer will be very different.
And many use 1 and 0, so there is many RIGHT answers.
Binary
Ternary
Quintal
Octal
Duodecimal
Hexadecimal
Base 36
Boolean
Denary
Just to name a few. Hope this helps.

Actually, since the original question only had 1's and 0's in it, the answer is still 14 no matter base is assumed. True, you may choose to write 14 as 0xA if you use hexidecimal or 1110 if you use binary or 16 if you use octal, but no matter what, the answer is still this many: ############## (Count them; there are fourteen of them).

I don't find it hilarious at all. I actually find it kind of sad. Order of operations is basic, basic math. Parentheses come first, then exponents, then multiplication and division (neither takes precedence over the other; they're simply done in order from left to right), then finally addition and subtraction (again, with neither taking precedence over the other).

Also, if you deliberately place the brackets, you are making it wrong, because:

-(1+1+1) = -1 -1 -1 =/= - 1 + 1 + 1

The answer is 14 you idiots.

The answer is 14 you idiots.

Indeed. Congratulations on reaching the same answer that was explained repeatedly throughout this thread.