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JavaScript JavaScript Basics (Retired) Working With Numbers The Random Challenge Solution

Nour El-din El-helw
Nour El-din El-helw
8,241 Points
Posted by Nour El-din El-helw
Nour El-din El-helw
8,241 Points

Why add 1?

Why should i add 1 in var randomNumber = Math.floor(Math.random() * (topNumber - bottomNumer + 1)) + bottomNumber; that's how i did it and it works well (got it from MDN) https://w.trhou.se/q6sphmij0r

2 Answers

Emil Pesaxov
Emil Pesaxov
3,684 Points

Basically, the function Math.random() gives you a random number between 0 and 1. That means all the float range of 0 to 1 not including 1. When you add Math.floor, you round the number down to the lowest integer, which will always be 0. If you want to get to 1 you would need to add 1.

So if you have something like Math.floor(Math.random() * 6); It will generate a number between 0 and 5 but it will never give you 6. If you want to display 6 as well, you would have to add + 1. Hope that helped. ;)

Tim Renner
Tim Renner
11,163 Points
Tim Renner
Tim Renner
11,163 Points

You add one to get the inclusive range, bottom number to top number. See also this previous question for more analysis of the formula...