The Problem Statement

The cockroach is one of the fastest insects. Write a function that takes its speed in km per hour and returns it in cm per second, rounded down to the integer (= floored).

For example:

1.08 --> 30 Note! The input is a Real number (actual type is language-dependent) and is >= 0. The result should be an Integer.

Analysis - Breaking Down The Question

We are asked to write a function that converts the km to cm per second and round it to the nearest integer.

Before we jump into the solution, it is important to understand the math here. The equation to convert kmph to cm/sec is to multiply the kmph by 5/18. It looks like (1.08x5/18)x100 -refer to the above example.

The Solution

Let's create a simple function that takes the cockroach's speed in kmph as shown below

  function cockroachSpeed(s) {

  }

Suppose, the cockroach's speed is 2km/hr then the calculation will be like this - (2x5/18)x100 = 55.555555. Let's see this in the function.

 function cockroachSpeed(s) {
    var speed = (s*5/18)*100; 
    console.log(speed) //55.5555555 if the s =2 
  }
cockroachSpeed(2)

But we want it to be rounded down to the nearest integer i.e; 55. For that, we can use Math. floor().

 function cockroachSpeed(s) {
    var speed = Math.floor((s*5/18))*100; 
    console.log(speed) // 55 
  }
cockroachSpeed(2)

We can return the speed as follows

 function cockroachSpeed(s) {
      var speed = (s*5/18)*100; 
      console.log(speed) //55.5555555 if the s =2 
      return speed;
  }
cockroachSpeed(2)

We can simplify the solution even more and write it in one line.

// Instead of writing 5/18*100 we can reduce this value to 27.777777778
// And instead of storing the value in variable speed, we can return it directly. 

// One line code
function cockroachSpeed(s) {
    return Math.floor(s*27.777778);
  }

Final Words

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