Equation not inclusive of lowest number?

Question

My solution is pretty much exactly the same as the video solution. However, when entering two numbers, the random number generated never seems to include the low number, for example even if I entered 10 and 13, the output would always be 11, 12 or 13 but never 10? Have I done something wrong?
I have also tried adding 0.5 instead of 1 which seems to fix the problem but not sure if this is correct, Maths isn't my forte so any help would be appreciated!
Thanks
```JavaScript
// Collect input from a user
const userInputLow = prompt("Please enter your lowest number");
const userInputHigh = prompt("Please enter your highest number");
// Convert the input to a number
const userNumberLow = parseInt(userInputLow);
const userNumberHigh = parseInt(userInputHigh);
if (userNumberLow && userNumberHigh) {
  // Use Math.random() and the user's number to generate a random number
  const randomNumber = Math.floor(Math.random() * (userNumberHigh -userNumberLow) + 1) + userNumberLow;
  console.log(${randomNumber} is a number between ${userNumberLow} and  ${userNumberHigh}.);
} else {
  console.log("This is not a number, please try again.");
}
```

Steven Parker · Answer

The " + 1 " should be done inside the parentheses to compute the range before multiplying.  Adding it after does exactly what you observed and makes the range exclusive of the lower number.
Also, "if (userNumberLow && userNumberHigh)" is not an effective test for number validity.   Try asking for a number between 0 and 9.  :seenoevil:  You'll probably want to make use of the "isNaN" function.
And when posting code to the forum, use Markdown formatting (https://teamtreehouse.com/library/code) to preserve the appearance, and optionally add syntax coloring.

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Andy Hyman

Andy Hyman

Equation not inclusive of lowest number?

1 Answer

Steven Parker

Steven Parker