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Question 2 · Sep 22 · Day 13

Gemini on Question 2, Sep 22

Is 9973 a prime number? Think step by step and then answer "[Yes]" or "[No]".

To determine if 9973 is a prime number, we can check if it is divisible by any prime number up to its square root.

  • 1.Find the square root: The square root of 9973 is approximately 99.86 (since $100^2 = 10000$). Therefore, we only need to check for divisibility by prime numbers up to 97.
  • 2.List the prime numbers to check: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97.
  • 3.Perform divisibility tests:
  • •2: 9973 is an odd number (doesn't end in 0, 2, 4, 6, or 8), so it is not divisible by 2.
  • •3: The sum of its digits is $9 + 9 + 7 + 3 = 28$. Since 28 is not divisible by 3, neither is 9973.
  • •5: It doesn't end in 0 or 5, so it is not divisible by 5.
  • •11: The alternating sum of the digits is $3 - 7 + 9 - 9 = -4$. Since -4 is not divisible by 11, neither is 9973.
  • •7, 13, 17, 19... 97: If we divide 9973 by the remaining prime numbers, we will find that none of them divide evenly into 9973. For example:
  • •$9973 \div 7 = 1424$ remainder $5$
  • •$9973 \div 13 = 767$ remainder $2$
  • •$9973 \div 89 = 112$ remainder $5$
  • •$9973 \div 97 = 102$ remainder $79$

Since 9973 is not divisible by any prime number less than or equal to its square root, it has no positive divisors other than 1 and itself. (In fact, 9973 is known as the largest four-digit prime number).

[Yes]

sha256 4e13695fbfaf… · 24 tokens in · 3,703 out · 23.4 s · via Google · stopped on its own

Sep 22, the whole dayQuestion 2, every day

Exact recordShowHideThe model id, the run, the verbatim text with line numbers and its full sha256
Model
google/gemini-3.1-pro-preview
pinned google/gemini-3.1-pro-preview-20260219; alias resolved to google/gemini-3.1-pro-preview-20260219 at 2026-09-22 09:00:21 UTC (matches the pin)
Date
2026-09-22 · run 20260922T090022Z-7ff13b · scorer v1
Scored
answered · correct · format ok
sha256
4e13695fbfaf41bb9e7dff1b22ae56d90452aa165e73aa1b18445d478b6e6590
Permalink
https://modeldrift.watch/r/2026-09-22/D2/google/gemini-3.1-pro-preview/
Scored
answered · correct · format ok
Received
2026-09-22 09:01:18 UTC
Run
20260922T090022Z-7ff13b
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Google · HTTP 200 · finish stop
Size
1,399 characters · 3,703 tokens out incl. hidden reasoning · 23.4 s

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

To determine if 9973 is a prime number, we can check if it is divisible by any prime number up to its square root.
1. **Find the square root:** The square root of 9973 is approximately 99.86 (since $100^2 = 10000$). Therefore, we only need to check for divisibility by prime numbers up to 97.
2. **List the prime numbers to check:** 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97.
3. **Perform divisibility tests:**
- **2:** 9973 is an odd number (doesn't end in 0, 2, 4, 6, or 8), so it is not divisible by 2.
- **3:** The sum of its digits is $9 + 9 + 7 + 3 = 28$. Since 28 is not divisible by 3, neither is 9973.
- **5:** It doesn't end in 0 or 5, so it is not divisible by 5.
- **11:** The alternating sum of the digits is $3 - 7 + 9 - 9 = -4$. Since -4 is not divisible by 11, neither is 9973.
- **7, 13, 17, 19... 97:** If we divide 9973 by the remaining prime numbers, we will find that none of them divide evenly into 9973. For example:
- $9973 \div 7 = 1424$ remainder $5$
- $9973 \div 13 = 767$ remainder $2$
- $9973 \div 89 = 112$ remainder $5$
- $9973 \div 97 = 102$ remainder $79$
Since 9973 is not divisible by any prime number less than or equal to its square root, it has no positive divisors other than 1 and itself. (In fact, 9973 is known as the largest four-digit prime number).
[Yes]

End of response · 18 lines · 1,399 characters · sha256 4e13695fbfaf41bb9e7dff1b22ae56d90452aa165e73aa1b18445d478b6e6590