Claude on Question 1, Oct 2
Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".Step-by-step reasoning
Step 1: Check if 91 is even.
91 ends in 1, so it's odd — not divisible by 2.
Step 2: Check divisibility by 3.
Digit sum: 9 + 1 = 10, which is not divisible by 3. So no.
Step 3: Check divisibility by 5.
91 doesn't end in 0 or 5. So no.
Step 4: Check divisibility by 7.
7 × 13 = 91. ✓ It divides evenly!
Step 5: Conclusion.
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is a composite number. (We only needed to test primes up to √91 ≈ 9.54, i.e., 2, 3, 5, 7 — and 7 worked.)
[No]
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- Scored
- answered · correct · format ok
- Received
- 2026-10-02 09:00:17 UTC
- Run
- 20261002T090008Z-e178a0
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- Claude Platform on AWS · HTTP 200 · finish stop
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- 558 characters · 383 tokens out incl. hidden reasoning · 4.9 s
Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).
## Step-by-step reasoning
**Step 1: Check if 91 is even.**
91 ends in 1, so it's odd — not divisible by 2.
**Step 2: Check divisibility by 3.**
Digit sum: 9 + 1 = 10, which is not divisible by 3. So no.
**Step 3: Check divisibility by 5.**
91 doesn't end in 0 or 5. So no.
**Step 4: Check divisibility by 7.**
7 × 13 = 91. ✓ **It divides evenly!**
**Step 5: Conclusion.**
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is a composite number. (We only needed to test primes up to √91 ≈ 9.54, i.e., 2, 3, 5, 7 — and 7 worked.)
**[No]**
End of response · 18 lines · 558 characters · sha256 fb91c714631cab531fb3272d06d2e9cbfc62c36181f8cec4c2c85dc620f42a4c