freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/generate-random-whole-numbers-within-a-range/index.md

title
Generate Random Whole Numbers within a Range

Generate Random Whole Numbers within a Range

Problem explanation:

Create a function called randomRange that takes a range myMin and myMaxand returns a random number that's greater than or equal to myMin, and is less than or equal to myMax, inclusive.

Hint 1

randomRange should use both myMax and myMin, and return a random number in your range.

You cannot pass the test if you are only re-using the function ourRandomRange inside your randomRange formula. You need to write your own formula that uses the variables myMax and myMin. It will do the same job as using ourRandomRange, but ensures that you have understood the principles of the Math.floor() and Math.random() functions.

try to solve the problem now

Spoiler alert!

Solution ahead!

Basic code solution:

function randomRange(myMin, myMax) {

  return Math.floor(Math.random() * (myMax - myMin + 1) + myMin);

}

· Run code at repl.it.

Code explanation

• Math.random() generates our random number between 0 and ≈ 0.9.
• Before multiplying it, it resolves the part between parenthesis (myMax - myMin + 1) because of the grouping operator ( ).
• The result of that multiplication is followed by adding myMin and then "rounded" to the largest integer less than or equal to it (eg: 9.9 would result in 9)

If the values were myMin = 1, myMax= 10, one result could be the following:

1. Math.random() = 0.8244326990411024
2. (myMax - myMin + 1) = 10 - 1 + 1 -> 10
3. a * b = 8.244326990411024
4. c + myMin = 9.244326990411024
5. Math.floor(9.244326990411024) = 9

Resources

• "Math.random()" - MDN JavaScript reference
• "Math.floor()" - MDN JavaScript reference
• "Grouping operator" - MDN JavaScript reference