Is 45 Prime?

Check if 45 is a prime number. A prime number is only divisible by 1 and itself.

Is prime?
Result: ✗ NO — 45 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 45 is prime, we need to verify that no number from 2 to √45 divides it evenly.

Step 2 Determine Testing Range

Since 45 is odd, we only need to check odd divisors.


We only need to test up to √45 ≈ 6.71, which rounds down to 6.


If 45 has a factor larger than √45, it must also have a corresponding factor smaller than √45.

Step 3 Test Odd Divisors

Testing: 3, 5, 7, ... up to 6


45 ÷ 3 = 15 (no remainder!)

We found that 3 divides 45 evenly!

Step 4 Conclusion
45 = 3 × 15

Since 45 has factors other than 1 and itself, 45 is NOT a prime number.