Claude on Question 1, Sep 29

Is 91 a prime number? Think step by step and then answer "[Yes]" or "[No]".

Step 1: Understand what's being asked.
A prime number has exactly two distinct positive divisors: 1 and itself. So I need to check whether 91 has any divisor other than 1 and 91.

Step 2: Determine how far to test.
I only need to test prime divisors up to √91. Since 9² = 81 and 10² = 100, √91 is between 9 and 10 (about 9.54). So I test the primes 2, 3, 5, 7.

Step 3: Test each prime.

•2: 91 is odd, so it's not divisible by 2.
•3: Digit sum = 9 + 1 = 10, which is not a multiple of 3, so 91 is not divisible by 3.
•5: 91 doesn't end in 0 or 5, so it's not divisible by 5.
•7: 7 × 13 = 91. ✓ Divisible!

Step 4: Conclude.
Since 91 = 7 × 13, it has divisors besides 1 and itself, so it is composite.

[No]

sha256 891b3e0cc19d… · 38 tokens in · 396 out · 5.5 s · via Claude Platform on AWS · stopped on its own

Sep 29, the whole day Question 1, every day

Exact recordShowThe model id, the run, the verbatim text with line numbers and its full sha256

Model: anthropic/claude-opus-5
pinned anthropic/claude-opus-5-20260723; alias resolved to anthropic/claude-opus-5-20260723 at 2026-09-29 09:00:07 UTC (matches the pin)
Date: 2026-09-29 · run 20260929T090007Z-334891 · scorer v1
Scored: answered · correct · format ok
sha256: 891b3e0cc19da7f4ab82a0c4f45f2966f13a07970641a320eb0e14304eddeaf9
Permalink: https://modeldrift.watch/r/2026-09-29/D1/anthropic/claude-opus-5/

Scored: answered · correct · format ok
Received: 2026-09-29 09:00:14 UTC
Run: 20260929T090007Z-334891
Served by: Claude Platform on AWS · HTTP 200 · finish stop
Size: 746 characters · 396 tokens out incl. hidden reasoning · 5.5 s

Highlighted: the last [Yes]/[No] bracket, which is the scored answer (No).

**Step 1: Understand what's being asked.**
A prime number has exactly two distinct positive divisors: 1 and itself. So I need to check whether 91 has any divisor other than 1 and 91.
**Step 2: Determine how far to test.**
I only need to test prime divisors up to √91. Since 9² = 81 and 10² = 100, √91 is between 9 and 10 (about 9.54). So I test the primes 2, 3, 5, 7.
**Step 3: Test each prime.**
- **2:** 91 is odd, so it's not divisible by 2.
- **3:** Digit sum = 9 + 1 = 10, which is not a multiple of 3, so 91 is not divisible by 3.
- **5:** 91 doesn't end in 0 or 5, so it's not divisible by 5.
- **7:** 7 × 13 = 91. ✓ Divisible!
**Step 4: Conclude.**
Since 91 = 7 × 13, it has divisors besides 1 and itself, so it is composite.
**[No]**

End of response · 16 lines · 746 characters · sha256 891b3e0cc19da7f4ab82a0c4f45f2966f13a07970641a320eb0e14304eddeaf9