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multiply ​

Multiplies a number by a scalar with precision handling for financial calculations. Supports both regular numbers and bigint for exact precision.

Implementation ​

View Source Code
ts
/**
 * Multiplies a number by a scalar with precision handling for financial calculations.
 * Supports both regular numbers and bigint for exact precision.
 *
 * @example
 * ```ts
 * multiply(10, 5); // 50
 * multiply(0.1, 3); // 0.3 (precision-safe)
 * multiply(100n, 5n); // 500n
 * ```
 *
 * @param a - Number to multiply
 * @param b - Multiplier
 * @returns Product of a and b
 */
export function multiply(a: number, b: number): number;
export function multiply(a: bigint, b: bigint): bigint;
export function multiply(a: number | bigint, b: number | bigint): number | bigint {
  if (typeof a === 'bigint' && typeof b === 'bigint') {
    return a * b;
  }
  if (typeof a === 'number' && typeof b === 'number') {
    return a * b;
  }
  throw new TypeError('Both arguments must be of the same type (number or bigint)');
}

Features ​

  • Type-Safe: Separate overloads for number and bigint
  • Precision: Works with bigint for financial calculations
  • Error Handling: Prevents mixing number and bigint types
  • Isomorphic: Works in both Browser and Node.js

API ​

ts
function multiply(a: number, b: number): number;
function multiply(a: bigint, b: bigint): bigint;

Parameters ​

  • a: Number to multiply (multiplicand)
  • b: Multiplier

Returns ​

  • Product of a times b (same type as input)

Examples ​

Basic Number Multiplication ​

ts
import { multiply } from '@vielzeug/toolkit';

multiply(10, 5); // 50
multiply(7, 8); // 56
multiply(0.1, 3); // 0.3 (precision-safe)

Negative Numbers ​

ts
import { multiply } from '@vielzeug/toolkit';

multiply(-10, 5); // -50
multiply(10, -5); // -50
multiply(-10, -5); // 50

BigInt for Financial Precision ​

ts
import { multiply } from '@vielzeug/toolkit';

// Calculate tax (8%)
const price = 50000n; // $500.00
const taxRate = 8n;

const tax = multiply(price, taxRate) / 100n;
// 4000n ($40.00)

Real-World Example: Bulk Pricing ​

ts
import { multiply } from '@vielzeug/toolkit';

const itemPrice = 1299n; // $12.99 per item
const quantity = 5n;

const total = multiply(itemPrice, quantity);
// 6495n ($64.95)

Calculate Discount ​

ts
import { multiply } from '@vielzeug/toolkit';

const originalPrice = 15999n; // $159.99
const discountPercent = 20n; // 20% off

const discountAmount = multiply(originalPrice, discountPercent) / 100n;
// 3199n ($31.99)

const finalPrice = originalPrice - discountAmount;
// 12800n ($128.00)

Implementation Notes ​

  • Both parameters must be the same type (number or bigint)
  • Throws TypeError if you try to mix number and bigint
  • For financial calculations with percentages, multiply first then divide
  • Multiplication by zero always returns zero
  • Multiplication by 1 returns the original value
  • Sign rules: negative × positive = negative, negative × negative = positive

See Also ​