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Card 587 of 9852026-09-16 issue

Observed arrival · 2026-09-16

A Calculator That Refuses to Stop at the Answer

opencalculator.app Observed source
Editorial interest 84/100 Selection signal · not a rating of the site

A free suite of 35 calculators for math, finance, grades, paychecks, dates, graphing, health, and everyday decisions.

Landing page captured for the 2026-09-16 issue.

Field notes

The suite organizes its calculators by practical context rather than presenting one undifferentiated form: finance includes compound interest, taxes, refunds, savings, and markups, while grades cover GPA, weighted grades, AP, SAT, and ACT scoring. Its compound-interest example accepts an initial balance, annual rate, term, and monthly contribution, then displays both the final amount and interest earned. The page states that completed answers can be exported as links, images, PDFs, or formula-bearing Excel sheets.

Observed signals

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Editorial observations of this landing page, not a rating.

OpenPublic substance visible
PrettyNotable craft visible
ProPolished or operationally mature
NicheUnusually specific use

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Wiring Is Not Learning

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opencalculator.app

Landing page observed 2026-09-16. The live site may have changed.