> ## Documentation Index
> Fetch the complete documentation index at: https://docs.truemath.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# What is TrueMath

> TrueMath is a deterministic math execution engine for AI-native workflows. LLMs reason and parse intent; TrueMath executes the math — at full precision, with provenance, against versioned business logic.

TrueMath is a deterministic mathematical execution engine. It is built to run in
partnership with large language models in the AI stack: the model reasons about a
request and parses intent, and TrueMath performs the actual calculation —
deterministically, at full precision, with provenance for every value, against
versioned business logic.

When someone asks "what would my monthly payment be if I put 15% down instead of
20%," an LLM understands the question and identifies the values involved. TrueMath
computes the answer and records how it got there.

<Note>
  **LLMs reason. TrueMath executes.** This is a division of responsibility, not a
  competition. See [How TrueMath fits with LLMs](/introduction/how-it-fits-with-llms).
</Note>

## What TrueMath is not

TrueMath is not a better calculator, and it is not a smarter language model. It is
execution infrastructure — the layer where correctness, reproducibility, and
auditability are enforced. A language model predicts likely text; TrueMath computes
guaranteed results. The two solve different problems, and TrueMath is built for the
one where "close" is not acceptable.

## How you work with it

You organize calculations into [domains](/concepts/domains) — collections of
[variables](/concepts/variables) (the values you calculate with) and
[activities](/concepts/activities) (the equations that relate them). TrueMath ships
a [library of pre-built domains](/domain-library/overview), and you can author your
own.

A calculation runs inside a [conversation](/concepts/scenarios). You provide values —
in natural language or as structured input — and name what you want to solve for.
TrueMath returns the result along with every variable's value, unit, and
[provenance](/concepts/provenance). Adjusting an input creates a new
[scenario](/concepts/scenarios), so you can explore what-if questions without losing
prior work.

You can use TrueMath three ways:

* **The Playground** — an interface for entering prompts and exploring calculations.
  Results are presented visually rather than narrated in prose — tables as tables,
  charts as charts — with the full underlying data available on demand.
* **The Builder** — an environment for authoring domains.
* **The API** — call TrueMath over HTTP from your own application or agent.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Run your first calculation in the Playground and through the API.
  </Card>

  <Card title="Core concepts" icon="diagram-project" href="/concepts/domains">
    Domains, activities, variables, provenance, and scenarios.
  </Card>

  <Card title="The guarantees" icon="shield-check" href="/introduction/guarantees">
    What "deterministic execution" actually gives you.
  </Card>

  <Card title="API reference" icon="code" href="/api/overview">
    Authenticate, run calculations, and read domains over HTTP.
  </Card>
</CardGroup>