Claude Opus 4.8 vs Kimi K3 for everyday maths
Effectively a dead heat: 100–98
Same 12 everyday maths tasks, marked blind by three rival labs. Claude Opus 4.8 took 3 tasks, Kimi K3 took 0, 9 tied. Tested 14 Aug 2026.
Where they differed most
Dinner cost £187.50 for 5 people, but one person only had a £12.50 main and drinks no alcohol; the other four agree to split the rest equally. What does each of the four pay? Show the working in two lines.
**Line 1:** Remaining amount = £187.50 − £12.50 = £175.00 **Line 2:** Each of the four pays = £175.00 ÷ 4 = **£43.75**
**Working:** £187.50 − £12.50 = £175.00 (the amount left for the four to split) £175.00 ÷ 4 = **£43.75 each**
Task by task
| Task | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| VAT both ways | 10 | 10 |
| Percentage change vs points | 10 | 10 |
| Unit price comparison | 10 | 10 |
| Mortgage overpayment intuition | 10 | 10 |
| Split a bill with a twist | 10 | 9 |
| Compound vs simple | 10 | 10 |
| The discount stack | 10 | 10 |
| Reverse percentage | 10 | 10 |
| Rate to reality | 10 | 10 |
| Average of averages trap | 10 | 10 |
| Estimate honestly | 10 | 9 |
| Refuse false precision | 10 | 9 |
Full receipts: Claude Opus 4.8, Kimi K3 · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for everyday maths: Claude Opus 4.8 or Kimi K3?
Effectively a dead heat: Claude Opus 4.8 edged it 100/100 to 98/100 on our everyday maths suite — too close to matter, so pick on price or the product you already use.
How was this tested?
Both models answered the identical published everyday maths tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More everyday maths head-to-heads: Claude Opus 4.8 vs GPT-5.6 Terra · Claude Opus 4.8 vs GPT-5.6 Sol · Claude Opus 4.8 vs GPT-5.6 Luna · Claude Opus 4.8 vs Grok 4.5 · Claude Opus 4.6 vs Claude Opus 4.8 · Claude Opus 4.8 vs GPT-5.3-Codex
Full ranking: Best AI for everyday maths · model pages: Claude Opus 4.8, Kimi K3