Numbers

JavaScript has just one numeric type, called number, covering both whole numbers and decimals. Unlike Java, there's no separate int vs double — 5, 5.0, and 5.5 are all simply a number.

const wholeNumber = 10;
const decimalNumber = 4.99;
console.log(typeof wholeNumber, typeof decimalNumber); // "number" "number"

The basic arithmetic operators are + (add), - (subtract), * (multiply), / (divide), % (remainder, also called modulo), and ** (exponent).

console.log(10 + 3); // 13
console.log(10 - 3); // 7
console.log(10 * 3); // 30
console.log(10 / 3); // 3.3333333333333335
console.log(10 % 3); // 1

NaN stands for "Not a Number" — a special number value produced by an invalid math operation, such as dividing zero by zero or trying to do arithmetic with something that has no meaningful numeric value. Confusingly, typeof NaN is itself "number".

console.log(0 / 0);      // NaN
console.log("abc" * 2);  // NaN

Dividing zero by zero, or performing math on non-numeric data, produces the special value ____.

Which statement about JavaScript's number type is true?

In JavaScript, 5 and 5.0 are stored using the exact same number type.