3. Data Types

3.2. Numbers


          A numerical value is a number. 

          As strings do, numbers are not associated with any special syntax. If you were to quote 5 (“5”), it would be a character in a string, not a number. It can be a decimal (float) or a whole and it can have positive or negative value.

var x = 5; // whole integer 

var y = 1.2; // float 

var z = -76; // negative whole integer

          Number can be up to 15 digits.

var largeNumber = 999999999999999; // a valid number


          How to write scientific notation in JavaScript?

        • e-notation indicates a floating-point value. 
        • E-notation displays a number raised to a given control that should be multiplied by 10. 
        • In JavaScript, the format of e-notation is to have a number, integer or floating-point, followed by e or E, then by the power to multiply by 10.

          Example: 

var floatNum = 7.215e7; //equal to 72150000 document.write(floatNum);

           In this case, 72,150,000 is equal to floatNum. In short, the notation states, "Take 7.215 and multiply it by 10^7."


          With numbers: addition (+), subtraction (-), division (/) and multiplication (+), you can do regular math.

var sum = 2 + 5; // displays 7 

var difference = 6 – 4 // displays 2

          With variables, you can do math like the example below:




  1. <!DOCTYPE html>
  2. <html>
  3.    <body>
  4.       <h2>Variables of JavaScript</h2>
  5.       <script>
  6.          var score1 = 3;
  7.          var score2 = 7;
  8.          var score3 = 9;
  9.          var score4 = 1;
  10.          var TotalScore = score1+score2+score3+score4; //displays 20
  11.          document.write(TotalScore);
  12.       </script>
  13.    </body>
  14. </html>

Two uncommon number type:

1. NaN

          While theoretically it’s a type of number, NaN means Not a Number. NaN is the product of attempting to do arithmetic with other data types.

var notNum = 5 / "Five"  // results NaN

          For instance, dividing a number by a string will result in NaN.

2. Infinity

          Technically, Infinity is a number, either the answer of dividing by 0 or calculating a number too large. 

var endless = 1 / 0;   // results Infinity