0.999... (with 9s repeating forever) is strictly less than 1.
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DISPROVED
The claim that 0.999...
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Every claim, machine-verified
// an AI skill that proves its work — every fact cited, every calculation re-runnable
106
Proofs
8
Domains
330
Sources checked
open source · auditable · re-runnable
how it works
claim
any factual assertion — from viral myths to mathematical theorems
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fetch sources
academic papers, government data, reference encyclopedias
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verify quotes
fetch each URL, match the exact quote on the live page
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run proof.py
executable Python — calculations you can re-run yourself
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verdict
proved, disproved, or partial — with full audit trail
think you know the answer?
Hover to reveal verdicts. Click to read the full proof.
Dark energy constitutes more than 68% of the universe's total energy density according to the Planck 2018 legacy release.
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PROVED (with unverified citations)
The Planck 2018 legacy release reports ΩΛ = 0.6853 ± 0.0074, which is strictly greater than 0.68.
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Hair and fingernails continue to grow for days after a person dies.
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DISPROVED (with unverified citations)
**DISPROVED (with unverified citations)**: The claim that hair and fingernails continue to grow for days after death is false.
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Humans use only 10% of their brain at any one time.
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DISPROVED
**Verdict: DISPROVED**
All 3 citations were verified against live sources (no unverified citations).
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Napoleon Bonaparte stood shorter than the average Frenchman of his era.
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DISPROVED (with unverified citations)
Napoleon Bonaparte was approximately 1.67-1.68 meters tall, which was 2-4 cm *taller* than the average Frenchman of his era (~1.641-1.65 meters).
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Quantum entanglement enables the transmission of usable information faster than the speed of light when the distant parties pre-agree on a measurement basis.
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DISPROVED
**Verdict: DISPROVED.** The claim that quantum entanglement enables faster-than-light information transmission when parties pre-agree on a measurement basis is false.
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The 100000th prime number is exactly 1299709.
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PROVED
The 100,000th prime number is exactly 1,299,709.
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The average person swallows eight spiders per year while sleeping.
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DISPROVED
The claim that the average person swallows eight spiders per year while sleeping is conclusively false.
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The Great Wall of China is the only man-made object visible from space with the naked eye.
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DISPROVED
The claim that the Great Wall of China is the only man-made object visible from space with the naked eye is false on both counts.
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The purchasing power of the US dollar has declined by more than 90% since the Federal Reserve was established in 1913.
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PROVED
**Verdict: PROVED.** The purchasing power of the US dollar has declined by **96.85%** since 1913, well exceeding the claimed "more than 90%" threshold by 6.85 percentage points.
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