Multiplication magic square

Answer: $\frac9{16}$

One way to find it:

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$2\times1\times r = 1\Rightarrow r=\frac12$

 

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 $p\times1\times\frac18=1\Rightarrow p=8$

 

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 $8\times s \times 2 = 1\Rightarrow s = \frac1{16}$

Therefore $r+s=\frac{1}{2}+\frac{1}{16}=\frac{9}{16}$