Which of the following numbers are not perfect cubes ? (I)64             (ii) 216           (iii) 243    (iv)  1728

Explanation

To determine which of the given numbers are not perfect cubes, we will find the prime factorization of each number and check if all the prime factors can be grouped into triplets.

### Step-by-Step Solution:

1. **Check 64:**
- Prime factorization of 64:
- 64 ÷ 2 = 32
- 32 ÷ 2 = 16
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