Update JavaScript Datatype -- Number (#6275)

Added Definition and Easy to Understand Examples for DataType Number.

src/data/roadmaps/javascript/content/number@GZ_SXsWmP7AsXRTc4WUMw.md

@@ -1 +1,25 @@
-# number
+# number
+
+The `Number` data type in JavaScript represents floating-point numbers, such as 37 or -9.25. The `Number` constructor provides constants and methods to work with numbers, and values of other types can be converted to numbers using the `Number()` function.
+
+### Example
+```JS
+let num1 = 255; // integer
+let num2 = 255.0; // floating-point number with no fractional part
+let num3 = 0xff; // hexadecimal notation
+let num4 = 0b11111111; // binary notation
+let num5 = 0.255e3; // exponential notation
+
+console.log(num1 === num2); // true
+console.log(num1 === num3); // true
+console.log(num1 === num4); // true
+console.log(num1 === num5); // true
+```
+
+In this example:
+
+- `255` and `255.0` are equivalent, as JavaScript treats both as the same number.
+- `0xff` represents `255` in hexadecimal notation.
+- `0b11111111` represents `255` in binary notation.
+- `0.255e3` is `255` in exponential notation.
+- All these different representations are equal to `255` in JavaScript.