Claude on Question 1, Oct 3
Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".Step 1: Check if 91 is even.
91 is odd, so it's not divisible by 2.
Step 2: Check divisibility by 3.
Digit sum: 9 + 1 = 10, which is not divisible by 3. So 91 is not divisible by 3.
Step 3: Check divisibility by 5.
91 doesn't end in 0 or 5, so it's not divisible by 5.
Step 4: Check divisibility by 7.
91 ÷ 7 = 13 exactly (since 7 × 13 = 91). ✓
So 91 = 7 × 13, meaning it has divisors other than 1 and itself.
(Note: we only needed to test primes up to √91 ≈ 9.54, i.e., 2, 3, 5, 7 — and 7 worked.)
Conclusion: 91 is composite, not prime.
[No]
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- Scored
- answered · correct · format ok
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- 2026-10-03 09:00:15 UTC
- Run
- 20261003T090008Z-b2d35e
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- Claude Platform on AWS · HTTP 200 · finish stop
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- 574 characters · 417 tokens out incl. hidden reasoning · 5.5 s
Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).
**Step 1: Check if 91 is even.**
91 is odd, so it's not divisible by 2.
**Step 2: Check divisibility by 3.**
Digit sum: 9 + 1 = 10, which is not divisible by 3. So 91 is not divisible by 3.
**Step 3: Check divisibility by 5.**
91 doesn't end in 0 or 5, so it's not divisible by 5.
**Step 4: Check divisibility by 7.**
91 ÷ 7 = 13 exactly (since 7 × 13 = 91). ✓
So 91 = 7 × 13, meaning it has divisors other than 1 and itself.
(Note: we only needed to test primes up to √91 ≈ 9.54, i.e., 2, 3, 5, 7 — and 7 worked.)
**Conclusion:** 91 is composite, not prime.
**[No]**
End of response · 19 lines · 574 characters · sha256 148385dd46c4370678dbc2fe330052ca7f8ef23a38292964084acb4eef955278