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#floating-point

2 stories

Banner: invoice total and payment receipt that differ by a single cent

Programming Languages Bug Report

JavaScript invoice totals off by one cent: floating point money rounding

Daniel Tran · Feb 18, 2025 · 8 min read

Our PDF invoices and the amounts charged through Stripe disagreed by a cent on 214 invoices in one month. Floats, toFixed and rounding at every step were to blame. We moved to integer minor units with one explicit rounding point.

Banner: trading bot order rejected because floating point math produced too many decimals

Programming Languages Bug Report

Precision is over the maximum defined for this asset: float math in a trading bot

Ryan Pham · Jan 30, 2025 · 5 min read

A grid trading bot written in TypeScript sent quantities like 0.30000000000000004 and got error -1111. Binary floating point cannot represent most decimal fractions, and serialising numbers to strings exposed it. A decimal library end to end and string serialisation fixed it.