Five India Calculators in Plain JavaScript — EMI, SIP, FD, GST and Age, With No Backend
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dev.to
Loan offers, mutual fund brochures, fixed-deposit tables, shop bills and exam forms all ask the same kind of question: "what does this number actually come to?" The answers are small pieces of arithmetic, but they are easy to get subtly wrong — a monthly rate used as an annual one, a SIP treated as a lump sum, an age counted in 30-day months. We built five calculators for India that run entirely in the browser, and this post is about the maths inside them: the formulas, the edge cases, and the p