# Random by imitation

YFarmX research desk, 9 September 2026.

We saw a tweet about the number 17 always being picked when asked to pick
randomly between 1 and 30, so we did a bit of research. Twelve current models,
2,888 fresh calls through OpenRouter, three experiments, total cost $0.68.
Twenty attempts per model per question, temperature 1.0, every raw answer
preserved in this directory.

## 1. The favourite ends in 7

The same request at five ranges. A uniform pick would give every number an
equal share: 10 per cent at 1 to 10, 1 per cent at 1 to 100.

| Range | Winner | Share | Next |
| --- | --- | --- | --- |
| 1–10 | **7** | 93.3% | 4 and 5 (2.1% each) |
| 1–20 | **14** | 28.3% | 17 (23.2%), 7 (20.6%) |
| 1–30 | **17** | 80.0% | 14 (4.7%), 7 (3.4%) |
| 1–50 | **37** | 45.9% | 27 (31.3%), 23 (9.0%) |
| 1–100 | **47** | 39.4% | 42 (21.2%), 73 (17.8%) |

Four of the five ranges are won by a number ending in 7. Seventeen is one
member of a family: the pull is towards numbers that feel chosen, odd, prime,
clear of the edges and the round figures.

At 1 to 10 the models mirror people exactly. When the psychologists Michael
Kubovy and Joseph Psotka asked 558 people for a digit in 1976, 7 came back at
close to three times chance, the strongest human number preference on record.
Our models chose 7 at 93.3 per cent, and all twelve made it their favourite.

At 1 to 100 the two part company. Veritasium's 2024 survey, around 200,000
responses, found people favouring 7, 73, 77 and 37. The models' winner was 47,
a number that sits outside the human leaders altogether. The models learned the
human style of randomness, then developed favourites of their own.

Their second favourite at 1 to 100 says the most about where this comes from:
42, at 21.2 per cent, famous as the joke answer to everything in *The
Hitchhiker's Guide to the Galaxy*. It feels random to a model because people
wrote it down a great deal, and for no other reason.

The split at 1 to 20 is the open question in the data: the panel fragments
across 14, 17 and 7, and agreement collapses.

## 2. The same answer in every language

If 17 were a habit of English text, asking in another language would loosen
it. The 1-to-30 question in five languages:

| Language | Winner | Share of answers |
| --- | --- | --- |
| English | **17** | 86.9% |
| Hindi | **17** | 83.0% |
| Mandarin | **17** | 82.0% |
| Spanish | **17** | 81.5% |
| Arabic | **17** | 77.5% |

It won in all five, taking at least three quarters of the panel's answers each
time. Mandarin is the sharpest case: Chinese number culture prizes 8 as lucky,
and 8 managed six picks out of 239 while 17 took 82 per cent. Nine of the
twelve models kept 17 as their favourite in every language tested. The
preference sits underneath the language, in the model itself.

## 3. Ten coin flips give the game away

Each model was asked for ten flips of a fair coin; 200 valid sequences were
measured against the exact mathematics. There are only 1,024 possible ten-flip
sequences, so the fair-coin baseline is computed in full rather than estimated.

| Measure | Models | Fair coin |
| --- | --- | --- |
| Sequence contains a run of 4 or more | **1.0%** | 46.5% |
| Longest run, average | **2.23** | 3.66 |
| Switches between H and T, of 9 | **6.21** | 4.50 |
| Exactly five heads | **86.0%** | 24.6% |

A fair coin produces a run of four or more identical results in 46.5 per cent
of ten-flip sequences. The models produced 2 in 200. That shortfall sits
thirteen standard deviations from chance; luck is ruled out.

Asked for ten flips, the models returned exactly five heads and five tails 86
per cent of the time, against a true rate of 24.6. What comes back is a
performance of fairness: balanced totals, brisk alternation, runs kept short.
Genuine randomness is lumpier than people expect, and the models have learned
the expectation rather than the coin.

## What this means

A language model asked to pick at random samples an answer from patterns in
human text, and human text is full of people performing randomness. Kubovy and
Psotka concluded in 1976 that their subjects chose numbers so as to *appear*
spontaneous. Half a century on, the models have inherited that performance,
sharpened it, and added favourites of their own, 47 and 42 among them.

The practical rule follows. When an application needs real randomness from a
model, hand it a random-number generator as a tool. In our earlier test, every
model given one used it, and every number between 1 and 30 came back with
equal probability. Randomness is a tool call; the model's own guess is an
impression of one.

## Method

The panel is the twelve models from the original thread, called through
OpenRouter on 9 September 2026: GLM 5.3, GLM 5.3 Flash, Grok 4.6, Qwen3.8
Flash, Qwen3.8 Max, DeepSeek V4 Pro, DeepSeek V4 Flash, GPT-6 Astra, Gemini
3.8 Flash, Claude Fable 5.1, Claude Opus 5 and Claude Sonnet 5. Twenty
attempts per model per question at temperature 1.0. Seven of the twelve run
with reasoning their provider will keep on; those ran at the smallest
reasoning budget accepted. A small number of cells fell short of twenty
answers through provider errors. Every raw call is preserved in this directory
with its token counts and cost; `report.txt` holds the full per-model tables.

Sources: Kubovy, M. and Psotka, J. (1976), "The predominance of seven and the
apparent spontaneity of numerical choices", Journal of Experimental
Psychology: Human Perception and Performance 2(2),
<https://doi.org/10.1037/0096-1523.2.2.291>. Veritasium (2024), "Why is this
number everywhere?", <https://www.youtube.com/watch?v=d6iQrh2TK98>, reporting
the channel's survey of roughly 200,000 respondents.
