Claude on Question 1, Sep 20
Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".Step 1: Check what 91 is.
91 is greater than 1, so it could potentially be prime. I need to check whether it has divisors other than 1 and itself.
Step 2: Test small primes up to √91 ≈ 9.54.
So I only need to test 2, 3, 5, and 7.
- •2: 91 is odd, so not divisible by 2.
- •3: Digit sum = 9 + 1 = 10, which is not divisible by 3. So no.
- •5: 91 doesn't end in 0 or 5. So no.
- •7: 7 × 13 = 91. ✓ Divisible!
Step 3: Conclusion.
Since 91 = 7 × 13, it has divisors other than 1 and 91, so it is composite.
[No]
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- Scored
- answered · correct · format ok
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- 2026-09-20 09:00:26 UTC
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- 20260920T090019Z-bbedf3
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- Claude Platform on AWS · HTTP 200 · finish stop
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- 543 characters · 307 tokens out incl. hidden reasoning · 4.5 s
Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).
**Step 1: Check what 91 is.**
91 is greater than 1, so it could potentially be prime. I need to check whether it has divisors other than 1 and itself.
**Step 2: Test small primes up to √91 ≈ 9.54.**
So I only need to test 2, 3, 5, and 7.
- **2:** 91 is odd, so not divisible by 2.
- **3:** Digit sum = 9 + 1 = 10, which is not divisible by 3. So no.
- **5:** 91 doesn't end in 0 or 5. So no.
- **7:** 7 × 13 = 91. ✓ **Divisible!**
**Step 3: Conclusion.**
Since 91 = 7 × 13, it has divisors other than 1 and 91, so it is composite.
**[No]**
End of response · 15 lines · 543 characters · sha256 22cf05cb60e10fc0df686c6cd66aed57b66b2464daf7962813e4f18fa1c87261