Is 129 Prime?
Check if 129 is a prime number. A prime number is only divisible by 1 and itself.
Result:
✗ NO — 129 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 129 is prime, we need to verify that no number from 2 to √129 divides it evenly.
Step 2
Determine Testing Range
Since 129 is odd, we only need to check odd divisors.
We only need to test up to √129 ≈ 11.36, which rounds down to 11.
If 129 has a factor larger than √129, it must also have a corresponding factor smaller than √129.
Step 3
Test Odd Divisors
Testing: 3, 5, 7, ... up to 11
129 ÷ 3 = 43 (no remainder!)
We found that 3 divides 129 evenly!
Step 4
Conclusion
129 = 3 × 43
Since 129 has factors other than 1 and itself, 129 is NOT a prime number.