TheAlgorithms/JavaScript · error · TypeError

Input must be Numbers

Error message

Input must be Numbers

What it means

The ModRing arithmetic methods (add, etc.) call isInputValid which requires both operands to be number primitives. This check fires after the modulus-initialization check. Note that BigInt values fail this check because typeof 3n is 'bigint', not 'number'.

Source

Thrown at Maths/ModularArithmetic.js:20

/**
 * https://brilliant.org/wiki/modular-arithmetic/
 * @param {Number} arg1 first argument
 * @param {Number} arg2 second argument
 * @returns {Number}
 */

export class ModRing {
  constructor(MOD) {
    this.MOD = MOD
  }

  isInputValid = (arg1, arg2) => {
    if (!this.MOD) {
      throw new Error('Modulus must be initialized in the object constructor')
    }
    if (typeof arg1 !== 'number' || typeof arg2 !== 'number') {
      throw new TypeError('Input must be Numbers')
    }
  }
  /**
   * Modulus is Distributive property,
   * As a result, we separate it into numbers in order to keep it within MOD's range
   */

  add = (arg1, arg2) => {
    this.isInputValid(arg1, arg2)
    return ((arg1 % this.MOD) + (arg2 % this.MOD)) % this.MOD
  }

  subtract = (arg1, arg2) => {
    this.isInputValid(arg1, arg2)
    // An extra MOD is added to check negative results
    return ((arg1 % this.MOD) - (arg2 % this.MOD) + this.MOD) % this.MOD
  }

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Pass number primitives (not strings or BigInts) to ModRing methods.
2. Convert string input with Number() before calling.
3. If working with large numbers, avoid BigInt; use plain numbers or a BigInt-compatible library instead.

Example fix

// before
ring.add(a, b) // a or b might be strings
// after
ring.add(Number(a), Number(b))

if (typeof arg1 !== 'number' || typeof arg2 !== 'number') {
  throw new TypeError('Both arguments must be numbers')
}
ring.add(arg1, arg2)

const areNumbers = (a, b) => typeof a === 'number' && typeof b === 'number'

When it happens

Trigger: Calling ring.add("3", 5), ring.add(3n, 5) (BigInt), ring.add(null, 5), or passing any non-number type as either argument.

Common situations: String numbers from user input, BigInt used for large modular arithmetic, or null/undefined from optional parameters that were not defaulted.

Related errors

• Input data must be numbers
• Invalid Input
• Argument must be an Array
• Argument is not a number.
• The ${paramName} should be type Number

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/13d0f25464f69652. Report an issue: GitHub.