Is 91 Prime?
Check if 91 is a prime number. A prime number is only divisible by 1 and itself.
Result:
✗ NO — 91 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 91 is prime, we need to verify that no number from 2 to √91 divides it evenly.
Step 2
Determine Testing Range
Since 91 is odd, we only need to check odd divisors.
We only need to test up to √91 ≈ 9.54, which rounds down to 9.
If 91 has a factor larger than √91, it must also have a corresponding factor smaller than √91.
Step 3
Test Odd Divisors
Testing: 3, 5, 7, ... up to 9
91 ÷ 3 = 30 remainder 1
91 ÷ 5 = 18 remainder 1
91 ÷ 7 = 13 (no remainder!)
We found that 7 divides 91 evenly!
Step 4
Conclusion
91 = 7 × 13
Since 91 has factors other than 1 and itself, 91 is NOT a prime number.