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Sandra Vu
3,525 PointsWhy need to add "+1" to generate the random number?
For example:
Get a random number up to 10
function getRandomNumber(10) { return Math.floor(Math.random()*10)+1; }
All of the similar examples in the video have "+1" in the formula. Why is it the case? Would this alone suffice?
return Math.floor(Math.random()*10)
2 Answers
Jennifer Nordell
Treehouse TeacherPaul Aguilar is correct. Math.random() generates a number between 0 and 1 but not including 1. So if we multiply it by 10 and then take the floor of it, we will only ever get a possible range of 0 to 9.
Adding the one not only increases the upper bound but also the lower bound. So let's say we generated a 0.001. Now when we multiply that by 10 (result: 0.01) and take the floor of that we get a 0. But adding the one guarantees that our lowest number will never be lower than 1. The same is true for .99. If we were to generate a .99 it would be calculated as 9.9. The floor of that is 9 and then we add a 1 which will put our maximum value at 10.
The +1 is there essentially to add one to both our lower bound and upper bound. Hope this helps!
Paul Aguilar
11,053 PointsMath.random() will never actually reach 1 it goes to .99 i believe but will never get to one, and so when you use Math.floor() with it to round down, you would want to add 1 to get to the highest possible number in the range you've selected.
Sandra Vu
3,525 PointsThanks Paul!