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This question was on my sister's 5th-grade homework, practicing order of operations. It was to make 18, using the numbers 1, 3, 4, 8 and the operations +, -, and *. The instructions imply using each operation only once. Additionally, grouping with parenthesis is allowed.

Neither my sister, my father, or I were able to find a solution. I even tried writing a python script to attempt all possible solutions to the problem, to no avail.

Can you do what we can't? Or is the problem flawed?

Edit: Here is a picture of the original worksheet. The problem in question is #11. I assume that operations are only allowed once, because some of the other problems have an operation repeated, and because it refers to rearranging operations and numbers on a mat. A photo of the original worksheet

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    $\begingroup$ Welcome to Puzzling.SE! I have a few questions - 1. Can the order of the numbers be changed? 2. Did you omit division on purpose or by accident? 3. Are there any other allowed operators (concatenation, exponents, roots, etc. $\endgroup$ – Brandon_J Mar 18 at 22:18
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    $\begingroup$ @Brandon_J, Order of numbers can be changed. Division and other operations intentionally omitted. $\endgroup$ – BillThePlatypus Mar 18 at 23:18
  • $\begingroup$ @ferret I've updated the question with the original worksheet. $\endgroup$ – BillThePlatypus Mar 18 at 23:18
  • $\begingroup$ I suspect that the teacher either meant 16 or 17, as both are possible. $\endgroup$ – Brandon_J Mar 19 at 2:02
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    $\begingroup$ I just added an answer. It was, in fact, a typo. $\endgroup$ – BillThePlatypus Mar 22 at 14:26
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Here it is.....

$18 * (4-3) = 18$

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    $\begingroup$ This works if concatenation is allowed. Considering it's a question for 5th graders, I doubt there is a "trick" like this, so I'm thinking it's a mistake by the teacher $\endgroup$ – ferret Mar 18 at 23:25
  • $\begingroup$ I agree with ferret. It is highly unlikely that concatenation is allowed, given the circumstances. $\endgroup$ – Brandon_J Mar 19 at 2:04
  • $\begingroup$ See, for example, problems five, six, and nine. If concatenation were allowed, there would be no need to join the digits of the 2-digit numbers together. $\endgroup$ – Brandon_J Mar 19 at 2:36
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    $\begingroup$ @Brandon_J and ferret, you are both probably right. Let's wait for the teacher's explanation :-) $\endgroup$ – ppgdev Mar 19 at 2:52
  • $\begingroup$ Yeah. Feel kinda bad for the teacher, tbh - I'm sure she'll feel bad for all the people that spent so much time on this. $\endgroup$ – Brandon_J Mar 19 at 3:02
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As I had suspected, the teacher confirmed that the question was incorrect, and there is no correct answer. Thank you all for the attempts.

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