round off a numhber in js code example

Example 1: how to displayan inteiger to a tenth in javascript

Math.round(3.14159 * 100) / 100  // 3.14

3.14159.toFixed(2);              // 3.14 returns a string
parseFloat(3.14159.toFixed(2));  // 3.14 returns a number

Math.round(3.14159)  // 3
Math.round(3.5)      // 4
Math.floor(3.8)      // 3
Math.ceil(3.2)       // 4

Example 2: calculate surface of a circle round to the nearest integer javascript

Math.round(Math.PI * radius * radius)