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Here is a follow up of Building the perfect number 28 with fractions

You are given the fractions $\frac{3}{2}, \frac{5}{2}, \frac{7}{2}, \frac{11}{2}.$

Use any operation of $+, -, *, /, ()$ to build 28 with those four fractions. You must use all four fractions exactly once.

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    $\begingroup$ Funnily, with this one, it seems quite easy to achieve with just three of the fractions but seems very difficult with four. $\endgroup$
    – hexomino
    Jan 15, 2020 at 11:57

1 Answer 1

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Perhaps there is a slight trick to this one

$\displaystyle\binom{\frac{11}{2} + \frac{5}{2}}{\frac{7}{2} - \frac{3}{2}} = \binom{8}{2} = 28$

where I've used () to denote a binomial coefficient.

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  • $\begingroup$ again, well done, it looks like those are too easy for you! $\endgroup$
    – ThomasL
    Jan 15, 2020 at 13:20

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