You can put this solution on YOUR website! You can plug sqrt(16/81) into the Google search line and it will tell you it = 0.4444444.
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You can look at the current equation as simply
or perhaps
which might give you the idea the answer is:
or
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Checking with a calculator (or the Google built-in calculator), you'll find 4/9 = 0.444444.
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Done.