About PocketMath

Everyday numbers, made clear.

PocketMath is a free collection of everyday calculators from FMFM Stars, operated by Fumiya Kobayashi in Japan. It helps you check a tip, divide a shared total, or understand a percentage discount without creating an account.

Useful results with visible steps

The calculators explain how each result is obtained. Money is handled as whole cents, percentage adjustments use an explicit round-half-up rule, and bill splits allocate leftover cents so the shares add back to the total. The rounding, bill-splitting, and discount guides explain those choices through worked examples.

Results use two decimal places. PocketMath does not convert currencies, connect to bank accounts, process payments, or determine a business’s tax or rounding policy. Use your receipt or the applicable offer to decide which inputs belong in the calculation.

Built for a quick check

Calculations run in your browser. PocketMath does not send your calculator entries to its server, save them in a database, or use browser storage to remember them. There is no subscription, account system, advertising script, or third-party analytics script in this version.

Supporting the site

The site includes an AdSense publisher ownership meta tag and an ads.txt file. These identify the publisher for verification; they do not themselves load advertisements. Any future advertising implementation will require corresponding updates to the site and its privacy notice.

Help improve PocketMath

A useful error report includes the tool name, example inputs, the result shown, and the result you expected. Send reports or suggestions to fmfm.stars@gmail.com. Use fictional amounts where possible and leave out account or payment details. See Contact for a simple reporting format.