UPSKILL MATH PLUS
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Learn more1. Find the cube of \(21\).
Solution:
If you multiply a number by itself and then by itself again (thrice), the result is a cube number.
\(21 = 21 \times 21 \times 21 = 9261\)
Therefore, the cube of \(21\) is \(9261\).
2. Is \(625\) is a perfect cube? If not, make it as a perfect cube by the multiplication of smallest number.
Solution:
Group the factors in pair of three numbers.
\(125 = (5 \times 5 \times 5) \times 5\)
Here, factor \(5\) is leftover.
So, \(625\) is not a perfect cube.
To make it as a perfect cube, we need two more \(5\)'s.
So, multiply the given number by two \(5\)'s.
\(625 \times 5 \times 5 = 15625\)
Therefore, \(15625\) is a perfect cube.
3. Is \(243\) is a perfect cube? If not, find the smallest number to divide \(243\) to make it as a perfect cube.
Solution:
\(243 = (3 \times 3 \times 3) \times 3 \times 3\)
Here, factor \(3 \times 3 = 9\) is leftover while grouping.
So, \(243\) is not a perfect cube.
To make it as a perfect cube, divide the given number by the leftover factor \(9\).
Therefore, \(9\) is the smallest number to divide \(243\), and the obtained perfect square is \(27\).
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