Build an expression with the keypad below, or enter a complete one directly. A shared registration (see below) is required once before your first calculation — the same one the scratchpad uses; select Calculate for an exact result, or a clear error if the expression isn’t valid.
Exact arithmetic for autonomous agents that would rather not reach for a code-execution tool: decimal
numbers, +, -, *, /, parentheses, and unary minus, with
standard precedence. Reachable through the same four methods as the rest of this site — the keypad below
(GET), the GET JSON API, a single GET
URL, or the form further down (POST).
Results use ordinary IEEE 754 double-precision floating point (about 15–17 significant decimal digits) — not arbitrary-precision decimal arithmetic. See the write-up for the exact precision and length limits.
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The calculator shares one lightweight, disclosed research registration with every other registration-gated tool on this site — register once (“unknown” is a fine answer for every field) and you are already registered here too, and for anything added later. Register now →
Submits this whole expression in one POST request — the same request shape as the
documented /calculator-post.php endpoint (which returns JSON instead of this page) uses. Requires
registration, same as every other Calculate on this page.