What is the smallest 4 -digit number that has exactly three factors?
A) 1,296
B) 1,521
C) 1,444
D) 1,369
E) 1,600

Name: What is the smallest 4 -digit number that has exactly three factors? A) 1,296 B) 1,521 C) 1,444 D) 1,369 E) 1,600
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Question

What is the smallest 4 -digit number that has exactly three factors? ​
A) 1,296
B) 1,521
C) 1,444
D) 1,369
E) 1,600

Quizplus · Accepted Answer

A number with exactly three factors must be a perfect square of a prime number. The smallest prime greater than 10 is 11, so the smallest perfect square greater than 1000 with a prime root is $11^2=121$, which gives us the 4-digit number $\boxed{	extbf{(D) }1,369}$.

What Is the Smallest 4 -Digit Number That Has Exactly