Hey there! I'm happy to help!
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INTRO TO PERFECT CUBES
A perfect cube is any number whose cube root is an integer. In English, that means that if you take any number without a fraction (this is called an integer, such as -7, 8, 100, none have fractions) and multiply it by itself three times, you get a perfect cube.
If you cube the number 4, you get 64, which is (4×4×4). 64 is an example of a perfect cube.
You can use the cube root button on your calculator to see if a number is a perfect cube. If you do the cube root of 64, you get 4, telling you that 64 is a perfect cube. The cube root of 10 is 2.154434...... so 10 is not a perfect square because it does not give you an integer (number that does not have a fraction) as the answer.
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SOLVING THE PROBLEM
So, we want to find the smallest numbers we can divide 8640 to equal a perfect cube.
I will assume that we will not be dividing by fractions but only whole numbers (positive integers).
We could try dividing by 1, but we see that 8640 is not a perfect cube because it's cube root is 20.519711....
Let's just keep counting up! The first divisor we run into that gives a quotient that it is a perfect cube is the smallest whole number possible that will give us that result.
8640÷2=4320
∛4320≈16.2865....... Not a perfect cube
8640÷3=2880
∛2880≈14.22757..... Not a perfect cube
8640÷4=2160
∛2160≈12.92660..... Not a perfect cube
8640÷5=1728
∛1728=12, a perfect cube!
Since 12 cubed is equal to 1728, this means that 1728 is a perfect square, so 5 is the smallest number we can divide 8640 by to get a perfect square.
The answer is 5.
I hope that this helps! Have a wonderful day! :D