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# Try this question on a friend posted to me on facebook

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Manager
Joined: 06 Jul 2011
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Location: Accra, Ghana
Try this question on a friend posted to me on facebook [#permalink]

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12 Apr 2012, 09:31
1+1+1+1+1+1+1+1+1+1-1+1+1+1+1+1*0=?

Some said the answer was 13, others say the answer is 0. Are there any Number Properties geniuses out there who can help with this crazy problem

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Verbal Forum Moderator
Joined: 23 Oct 2011
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Re: Try this question on a friend posted to me on facebook [#permalink]

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12 Apr 2012, 10:00
IMO answer is 13. As far as I can see, there are no tricks in this problem.
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Kudos [?]: 962 [0], given: 23

Current Student
Joined: 12 Sep 2011
Posts: 900

Kudos [?]: 958 [0], given: 114

Concentration: Finance, Finance
GMAT 1: 710 Q48 V40
Re: Try this question on a friend posted to me on facebook [#permalink]

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12 Apr 2012, 10:25
PEMDAS - Parenthesis, exponents, multiplication, division, addition, subtraction

This is what "order of operations" that you should do all math work in.

So first you'd do 1*0 = 0, then you'd add all the 1's together.

I see the answer as 15, but only because you have 16 ones and 1 zero.

The reason why this question is slightly confusing, is if you didn't know the order to do the work you would add up all the 1's, and then multiply by zero. Obviously, anything multiplied by 0 is 0, but in this case you adding to that 0 once that operation is completed.

If you change the problem to (1+1+1+1...+1)*0, then you'd do the parenthesis first, and end up with 0 as your answer.
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Kudos [?]: 958 [0], given: 114

Manager
Joined: 06 Jul 2011
Posts: 213

Kudos [?]: 71 [0], given: 39

Location: Accra, Ghana
Re: Try this question on a friend posted to me on facebook [#permalink]

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12 Apr 2012, 11:32
GMATLA wrote:
PEMDAS - Parenthesis, exponents, multiplication, division, addition, subtraction

This is what "order of operations" that you should do all math work in.

So first you'd do 1*0 = 0, then you'd add all the 1's together.

I see the answer as 15, but only because you have 16 ones and 1 zero.

The reason why this question is slightly confusing, is if you didn't know the order to do the work you would add up all the 1's, and then multiply by zero. Obviously, anything multiplied by 0 is 0, but in this case you adding to that 0 once that operation is completed.

If you change the problem to (1+1+1+1...+1)*0, then you'd do the parenthesis first, and end up with 0 as your answer.

GMATLA, thanks for your input. I rushed on this question and made the same mistake, but after careful analysis I later saw what made it slightly confusing. I really feel dumb for even getting this wrong, but hey I am learning something daily or having basic concepts reinforced to me.

Kudos [?]: 71 [0], given: 39

Senior Manager
Joined: 01 Apr 2010
Posts: 297

Kudos [?]: 59 [0], given: 11

Location: Kuwait
Schools: Sloan '16 (M)
GMAT 1: 710 Q49 V37
GPA: 3.2
WE: Information Technology (Consulting)
Re: Try this question on a friend posted to me on facebook [#permalink]

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17 Apr 2012, 11:58
definately 15. Not as contraversial as
6÷2(1+2)=
1 or 9

Division should be before Multiplication but some suggest a paranthesis multiplication takes priority.

Kudos [?]: 59 [0], given: 11

Director
Status: Can't wait for August!
Joined: 13 Sep 2011
Posts: 988

Kudos [?]: 351 [0], given: 109

Location: United States (MA)
Concentration: Marketing, Strategy
GMAT 1: 660 Q44 V37
GMAT 2: 680 Q45 V38
GMAT 3: 710 Q45 V42
GPA: 3.32
WE: Information Technology (Retail)
Re: Try this question on a friend posted to me on facebook [#permalink]

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26 Apr 2012, 11:43
GMATLA wrote:
PEMDAS - Parenthesis, exponents, multiplication, division, addition, subtraction

This is what "order of operations" that you should do all math work in.

So first you'd do 1*0 = 0, then you'd add all the 1's together.

I see the answer as 15, but only because you have 16 ones and 1 zero.

The reason why this question is slightly confusing, is if you didn't know the order to do the work you would add up all the 1's, and then multiply by zero. Obviously, anything multiplied by 0 is 0, but in this case you adding to that 0 once that operation is completed.

If you change the problem to (1+1+1+1...+1)*0, then you'd do the parenthesis first, and end up with 0 as your answer.

In the OP one of the 1s is a -1, making the answers 13 not 15.

Someone posted this on FB a few weeks ago, with the caption "Why are so many people making a big deal out of this, its easy math, the answer is 0. Anything * 0 = 0"

Kudos [?]: 351 [0], given: 109

Director
Status: Can't wait for August!
Joined: 13 Sep 2011
Posts: 988

Kudos [?]: 351 [0], given: 109

Location: United States (MA)
Concentration: Marketing, Strategy
GMAT 1: 660 Q44 V37
GMAT 2: 680 Q45 V38
GMAT 3: 710 Q45 V42
GPA: 3.32
WE: Information Technology (Retail)
Re: Try this question on a friend posted to me on facebook [#permalink]

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26 Apr 2012, 11:46
aalba005 wrote:
definately 15. Not as contraversial as
6÷2(1+2)=
1 or 9

Division should be before Multiplication but some suggest a paranthesis multiplication takes priority.

I think the rule is anything inside a paranthesis comes first, and doesnt include anything outside. Writing 3*3 is the exact same thing as writing 3(3). Atleast that's always been my understanding

Kudos [?]: 351 [0], given: 109

Intern
Joined: 15 Jan 2012
Posts: 9

Kudos [?]: [0], given: 0

Re: Try this question on a friend posted to me on facebook [#permalink]

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26 Apr 2012, 20:32
It is 13.How to account as 0 .I am puzzled.

Kudos [?]: [0], given: 0

Re: Try this question on a friend posted to me on facebook   [#permalink] 26 Apr 2012, 20:32
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