Question 156509
 The box with a volume of 70 inches. Volume = length width and height each side is a prime number of inches long what is each sides length?
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There's no way to calculate this, it's a trial and error approach.
First, 70 is an even number, so one of the sides has to be an even number.  The only even prime number is 2, so that's one of the sides.
70/2 = 35.  The only 2 factors of 35 are 5 and 7, so that's the answer.
The box is 2 x 5 x 7.