Fintech Web Systems Skill

In fintech, a rounding error is a financial error. Latency is money. Build these systems with precision as a first-class requirement, not an afterthought.

CHUNK 1: Financial Arithmetic — Never Use Native Floats

// WRONG — floating-point kills fintech
const price    = 19.99;
const quantity = 3;
const total    = price * quantity;  // → 59.97000000000001 !!!

// RIGHT — use Decimal.js for all calculations
import Decimal from 'decimal.js';