Do not recompute the sum in your client
2026-03-14 · Arithmetic captchas
text is already the result. A second calculator creates a second source of truth.
It is tempting to parse expression and add the numbers again. That parser will disagree on a hyphen, a unicode minus, or a multiplication star, and you will submit a different string from the one you were charged for.
Submit text unchanged. If you do not believe it, refresh the captcha. Do not edit the digits.
Tests can assert that text equals the evaluation of expression for your own fixtures. Production traffic should not depend on that assertion to rewrite the answer.
A mismatch in a fixture is a bug to look at, not a string to patch at the call site.
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