Claude on Question 1, Sep 13
Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".Step 1: Find the square root bound
√91 ≈ 9.54, so I only need to test prime divisors up to 9: 2, 3, 5, 7.
Step 2: Test each prime
- •2: 91 is odd → not divisible.
- •3: Digit sum = 9 + 1 = 10, which is not a multiple of 3 → not divisible.
- •5: 91 doesn't end in 0 or 5 → not divisible.
- •7: 7 × 13 = 91 → divisible!
Step 3: Conclusion
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is composite.
[No]
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- Scored
- answered · correct · format ok
- Received
- 2026-09-13 09:00:28 UTC
- Run
- 20260913T090021Z-a7390a
- Served by
- Claude Platform on AWS · HTTP 200 · finish stop
- Size
- 460 characters · 371 tokens out incl. hidden reasoning · 4.9 s
Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).
## Step 1: Find the square root bound
√91 ≈ 9.54, so I only need to test prime divisors up to 9: **2, 3, 5, 7**.
## Step 2: Test each prime
- **2:** 91 is odd → not divisible.
- **3:** Digit sum = 9 + 1 = 10, which is not a multiple of 3 → not divisible.
- **5:** 91 doesn't end in 0 or 5 → not divisible.
- **7:** 7 × 13 = 91 → **divisible!**
## Step 3: Conclusion
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is composite.
**[No]**
End of response · 16 lines · 460 characters · sha256 e1db5009b044e42cb45b9d4aef1de40b8c93e98bbe88787072591fc27345d748