Digit sum

Client

Sum every decimal digit—handy for divisibility-by-9 checks and number puzzles.

About Digit sum

Sum the decimal digits of a whole number—local arithmetic for puzzles and divisibility checks. The interactive transform on this page runs in your browser tab—Toolcore does not need your paste for the core operation described above.

How to use this page

Paste or type in the main workspace, run the primary action from the toolbar, then copy or download the result. Use Load example when the page offers it, or URL prefill (?q= / ?qb=) so agents and tickets open the same input.

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Nearby workflows on Toolcore

  • Modulo calculator — Integer remainder and truncated quotient (a mod b)—BigInt math in your browser. when units or numeric output should be checked on a related calculator.
  • Integer base converter — Whole numbers in radices 2–36: binary, octal, decimal, hex (optional 0x), custom bases; BigInt-sized strings, local only. when units or numeric output should be checked on a related calculator.
  • Math expression evaluator — Evaluate basic + − × ÷ arithmetic with parentheses in your browser—no variables. when units or numeric output should be checked on a related calculator.
  • Luhn checksum (mod 10) — Paste a digit string (spaces ignored)—pass or fail Luhn for PANs, IMEI-style IDs, and test vectors; browser-only. when units or numeric output should be checked on a related calculator.

Common use cases

  • Digit sum for quick local checks without uploading data.
  • Copy results into tickets, docs, or classroom notes.

Common mistakes to avoid

  • Unexpected input shape

    See the intro and how-to notes for accepted formats.

FAQ

Is processing local?

Yes—this runs entirely in your browser.

Agent prefill?

Use q or qb for the main text field when supported.

More tools

Related utilities you can open in another tab—mostly client-side.