Functions that deal with numbers when accuracy is more important than speed

accounting.js

class Accounting {
  static largestNumber = 10e9; // America's annual budget is ~4tn
  static accuracy = (function() {
    let accuracy = 1;
    while (Accounting.largestNumber * accuracy < Number.MAX_SAFE_INTEGER) {
      accuracy *= 10;
    }
    return accuracy;
  }()); // to change to #accuracy when support rises

  static sum(...args) {
    let arg = args.pop();
    let currentSum = arg * Accounting.accuracy;

    while(!isNaN(arg = args.pop())) {
      currentSum += arg * Accounting.accuracy;
    }

    return currentSum / Accounting.accuracy;
  }

  static subtract(...args) {
    let arg = args.shift();
    let currentSum = arg * Accounting.accuracy;

    while(!isNaN(arg = args.shift())) {
      currentSum -= arg * Accounting.accuracy;
    }

    return currentSum / Accounting.accuracy;
  }

  static multiply(...args) {
    let arg = args.pop();
    let currentSum = arg * Accounting.accuracy;

    while(!isNaN(arg = args.pop())) {
      currentSum *= arg;
    }

    return currentSum / Accounting.accuracy;
  }

  static divide(...args) {
    let arg = args.shift();
    let currentSum = arg * Accounting.accuracy;

    while(!isNaN(arg = args.shift())) {
      currentSum /= arg;
    }

    return currentSum / Accounting.accuracy;
  }
}