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Find the smallest number by which the number 1296 must be divided to obtain a perfect cube.

Answer»

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In order to find the smallest number by which the number 1296 must be divided to obtain a perfect cube, we'll FIRST find the prime factors of the given number by prime factorization.

\large \begin{array}{c| c}  \underline{\sf{2}}& \underline{ \sf{1296}} \\ \underline{\sf{2}}& \underline{ \sf{ \: 648 \: }} \\ \underline{\sf{2}}& \underline{ \sf{ \: 324 \: }} \\ \underline{\sf{3}}& \underline{ \sf{ \: 162 \: }} \\ \underline{\sf{3}}& \underline{ \sf{ \:  \: 54 \:  \: }} \\ \underline{\sf{3}}& \underline{ \sf{ \:  \: 18 \:  \: }} \\ \underline{\sf{3}}& \underline{ \sf{ \:  \:  \: 6 \:  \: \:  }}  \\ \underline{\sf{2}}& \underline{ \sf{ \:  \:  \: 2  \: \:  \: }} \\  \: & \sf1\end{array}

By prime factorization, we get :

\longrightarrow 1296 = 2 × 2 × 2 × 3 × 3 × 3 × 3 × 2

\longrightarrow 2 × 2 × 2 × 3 × 3 × 3 × 6

So, 6 is the smallest number by which the number 1296 must be divided to obtain a perfect cube.

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Procedure to solve this type of questions:

• Find the prime factors.

• Form groups of three like factors.

• The number which can't be FORMED as a group of three like factors is the number which must be divided to obtain a perfect cube.



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