N is a natural number which has 6 factors. If 10 ≤ N ≤ 50, then how many values are possible for N?
Explanation:
Since N has 6 factors,
6 can be factorized as 6 or 2 × 3.
∴ N must be of the form P15 or P2 × P32 where P1, P2, P3 are prime numbers.
If N takes the form P15 then P1 can only be 2. [10 ≤ N ≤ 50]
If N takes the form P2 × P32 then the possibilities are: 2 × 32, 2 × 52, 3 × 22, 5 × 22, 5 × 32, 7 × 22, 11 × 22
So, N can take 1 + 7 = 8 values in all.
Hence, 8.
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