Claude on Question 1, Sep 27
Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".Step-by-step check
To test whether 91 is prime, I only need to check prime divisors up to √91 ≈ 9.54, so: 2, 3, 5, 7.
Divisible by 2? 91 is odd → No.
Divisible by 3? Digit sum = 9 + 1 = 10, which is not a multiple of 3 → No.
Divisible by 5? It doesn't end in 0 or 5 → No.
Divisible by 7? 7 × 13 = 91 → Yes!
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is composite (it's a common "looks prime but isn't" number).
[No]
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- Scored
- answered · correct · format ok
- Received
- 2026-09-27 09:00:14 UTC
- Run
- 20260927T090007Z-7adb14
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- Claude Platform on AWS · HTTP 200 · finish stop
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- 472 characters · 356 tokens out incl. hidden reasoning · 5.2 s
Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).
## Step-by-step check
To test whether 91 is prime, I only need to check prime divisors up to √91 ≈ 9.54, so: 2, 3, 5, 7.
**Divisible by 2?** 91 is odd → No.
**Divisible by 3?** Digit sum = 9 + 1 = 10, which is not a multiple of 3 → No.
**Divisible by 5?** It doesn't end in 0 or 5 → No.
**Divisible by 7?** 7 × 13 = 91 → **Yes!**
Since 91 = 7 × 13, it has divisors other than 1 and itself, so it is composite (it's a common "looks prime but isn't" number).
**[No]**
End of response · 15 lines · 472 characters · sha256 964d221c22f9fc9157481d7dc33b3d40b1555d4ce1d54461b350e55c0b7d9a70