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I'm worried that this will be a spanner in the works when I'm using a calculator in an exam , I know that $-2^2= 4$ since $(-2) \cdot (-2) = 4 $. So why does my calculator show it as negative 4 ? Does anyone know if there is a way to reset my calculator so it doesn't do this? The make and model is Casio fx-83ES.

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    $\begingroup$ $(-2)^2 = 4$, but $-2^2 = -(2^2) = -4$, the precedence of exponentiation is higher than that of unary minus. $\endgroup$ – Daniel Fischer Oct 15 '15 at 22:09
  • $\begingroup$ I see, Thanks ! $\endgroup$ – Flewitt Connor Oct 15 '15 at 22:26
  • $\begingroup$ It depends on how the calculator parses the input; for instance echo '-2^2' | bc returns 4. $\endgroup$ – egreg Mar 13 '16 at 21:38
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There is a difference between $-2^2$ and $(-2)^2$ In the first examples you square the number two and then you apply the negative. In the second example you sqaure the number negative two then you get the desired reuslt, 4

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This is a really simple error to correct. It's order of operations: $-2^2=-(2^2)=-4$. Your calculator is correct, just use parentheses around $-2$. $(-2)^2=4≠-2^2$.

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Note that $-2^2$ is different than $(-2)^2$, which you intend.

Reviewing the order of operations, exponentiation comes before multiplication. $-2^2 = -1 \cdot 2^2 = -1 \cdot 4 = -4$.

However $(-2)^2$ is evaluated as $(-2)^2 = 4$.

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  • $\begingroup$ Thank you I expected It to be something relatively simple, this has cleared things up a lot :) $\endgroup$ – Flewitt Connor Oct 15 '15 at 22:27

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