what a tricky challenge is!! need a comment what's something wrong!

Hey Analyn

Imagine that Math.random() returns something close to 1. Then your result would be higher than highNum. Let me clarify... let's assume the user inputs 20 and 100, and the Math.random() returns 0.9999999999 (you get the idea) then you would end up with a random number of 119.

var lowNum = 20;
var highNum = 100;
var randomNum = Math.floor(0.999999999 * 100) + 20;

To fix this you need to think of the multiplier for Math.random() as a range you want your result to fall within. In this case it would be (and im just typing out the numbers here to make the math easier to understand):

var lowNum = 20;
var highNum = 100;
var validRange = 100 - 20;
var randomNum = Math.floor(0.999999999 * 80) + 20;

The random number above is 79 + 20 = 99, which is valid - but note that it can never be exactly 100. This is because Math.random() never returns 1, and Math.floor rounds everything down. To fix this you need to add 1 to the range. So:

var lowNum = parseInt( prompt('Please enter a number from 1 to 20'));
var highNum = parseInt( prompt('Please enter a number from 100 to 200'));
var validRange = highNum - lowNum + 1
var randomNum = Math.floor(Math.random() * validRange) + lowNum;

Makes sense?