Answer :

Answer:

5

Step-by-step explanation:

To find the smallest number by which 84375 must be multiplied to make the product a perfect cube, we need to perform prime factorization and then determine the necessary adjustments to each prime factor so that the overall product is a perfect cube.

1. **Prime Factorization of 84375:**

- Divide by the smallest prime numbers repeatedly until the quotient is 1.

Let's start with \( 84375 \):

\( 84375 \div 3 = 28125 \) (since \( 8+4+3+7+5 = 27 \), divisible by 3)

\( 28125 \div 3 = 9375 \)

\( 9375 \div 3 = 3125 \)

\( 3125 \div 5 = 625 \)

\( 625 \div 5 = 125 \)

\( 125 \div 5 = 25 \)

\( 25 \div 5 = 5 \)

\( 5 \div 5 = 1 \)

So, the prime factorization is:

\[

84375 = 3^3 \times 5^5

\]

2. **Adjusting the prime factors to form a perfect cube:**

- A perfect cube must have each prime factor raised to a power that is a multiple of 3.

- For \( 3^3 \), it's already a cube.

- For \( 5^5 \), to make it a cube, we need to raise it to the nearest multiple of 3. The next multiple of 3 greater than 5 is 6. Thus, we need an additional \( 5^1 \).

3. **Determine the smallest multiplier:**

- The smallest number by which 84375 must be multiplied to make it a perfect cube is \( 5^1 = 5 \).

4. **Verification:**

- The product is \( 84375 \times 5 = 421875 \).

- Prime factorization of 421875:

\[

421875 = 3^3 \times 5^6

\]

- Both prime factors \( 3^3 \) and \( 5^6 \) are perfect cubes, so 421875 is a perfect cube.

Therefore, the smallest number by which 84375 must be multiplied to make it a perfect cube is \( \boxed{5} \).

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