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Next year is the 70th anniversary of the publication of the book 1984 by George Orwell. Here is a puzzle to start the anniversary celebrations off a bit early ...

Warm up

Can you assemble a formula using the numbers $1$, $9$, $8$, and $4$ in any order so that the results equals $246$. You may use the operations $x + y$, $x - y$, $x \times y$, $x \div y$, $x!$, $\sqrt{x}$, $\sqrt[\leftroot{-2}\uproot{2}x]{y}$ and $x^y$, as long as all operands are either $1$, $9$, $8$, or $4$. Operands may of course also be derived from calculations e.g. $19*8*(\sqrt{4})$. You may also use brackets to clarify order of operations, and you may concatenate two or more of the four digits you start with (such as $8$ and $4$ to make the number $84$) if you wish. You may only use each of the starting digits once and you must use all four of them. I'm afraid that concatenation of numbers from calculations is not permitted, but answers with concatenations will get plus one from me.

Main Event

If you used concatenation above then make a formula using the numbers $1$, $9$, $8$, and $4$ in any order so that the results equals $246$ without using any concatenation. so, for example, you cannot put $8$ and $4$ together to make the number $84$. The rest of the rules above apply, but concatenation is not allowed. If you didn't use any concatenation above then you have solved the puzzle, but you could try to solve it with concatenation, that is concatenation of the initial numbers only.

Note (and perhaps hint): For this second part any finite number of functions can be used, though ingenious solutions with infinite numbers of functions will get plus one from me.

Note that in all the puzzles above Double, triple, etc. factorials (n-druple-factorials), such as $4!! = 4 \times 2$ are not allowed, but factorials of factorials are fine, such as $(4!)! = 24!$. I will upvote answers with double, triple and n-druple-factorials which get the required answers, but will not mark them as correct - particularly because a general method was developed by @Carl Schildkraut to solve these puzzles.

many thanks to the authors of the similar questions below for inspiring this question.

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2 Answers 2

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Here is how:

$\left(\sqrt{4}\right)^8-(9+1)$

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  • $\begingroup$ I dont know how to format math stuff $\endgroup$
    – PotatoLatte
    Sep 19, 2018 at 22:40
  • $\begingroup$ Think this should help, @PotatoLatte. $\endgroup$
    – El-Guest
    Sep 19, 2018 at 22:42
  • $\begingroup$ Thanks! (But on a phone is just looks like the text in the editing thing) $\endgroup$
    – PotatoLatte
    Sep 19, 2018 at 22:43
  • $\begingroup$ Oh never mind... $\endgroup$
    – PotatoLatte
    Sep 19, 2018 at 22:43
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    $\begingroup$ @El-Guest yes--- of course... will have to go back to the drawing board for this one.... $\endgroup$
    – tom
    Sep 19, 2018 at 22:46
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Assuming repeating decimals are allowed:

$\large\left(\sqrt{4}\right)^8-\frac{.\overline{9}\cdots}{.1}=$

$\large2^8-\frac{1}{.1}=$

$\large256-10=$

$\large246$

I acknowledge that the answer by PotatoLatte is nicer.

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  • $\begingroup$ thanks for the answer. interesting... $\endgroup$
    – tom
    Nov 10 at 19:24

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