Question 1200504
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A box with a square base and no top is to be made from a square piece of carboard 
by cutting 4 in. squares from each corner and folding up the sides. 
The box is to hold 17956 in3. How big a piece of cardboard is needed?
Your answer is [ ]in. By [ ]in.
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            Solve it  MENTALLY.



<pre>
It is OBVIOUS that the height of the box is 4 inches.

Hence, the base area of the box is  {{{17956/4}}} = 4489 square inches.


Then the size of the square base is  {{{sqrt(4489)}}} = 67 inches.


It means that the original cardboard is the square of the side 67 + 4 + 4 = 75 inches.


<U>ANSWER</U>.  The original cardboard is the square of the side of 75 inches.
</pre>

Solved MENTALLY.


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You need a calculator to extract the square root, but you do not need to solve and even to write any equations.