Is 15 Prime?
Check if 15 is a prime number. A prime number is only divisible by 1 and itself.
Result:
✗ NO — 15 is NOT a prime number
Step-by-Step Solution
Step 1
What is a Prime Number?
A prime number is a natural number greater than 1 that has exactly two factors: 1 and itself.
To check if 15 is prime, we need to verify that no number from 2 to √15 divides it evenly.
Step 2
Determine Testing Range
Since 15 is odd, we only need to check odd divisors.
We only need to test up to √15 ≈ 3.87, which rounds down to 3.
If 15 has a factor larger than √15, it must also have a corresponding factor smaller than √15.
Step 3
Test Odd Divisors
Testing: 3, 5, 7, ... up to 3
15 ÷ 3 = 5 (no remainder!)
We found that 3 divides 15 evenly!
Step 4
Conclusion
15 = 3 × 5
Since 15 has factors other than 1 and itself, 15 is NOT a prime number.