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Start your free trial###### Tomasz Grodzki

8,130 Points# Why Math.floor ( Math.random() * 6 ) + 1; works good but Math.floor ( Math.random() * 6 ) + 4; doesn't?

In this lesson we've got such a code: var number = Math.floor ( Math.random() * 6 ) + 1; - and this code draws numbers from 1 to 6... okay, everything's clear. But why this code: var number = Math.floor ( Math.random() * 6 ) + 4; doesn't draws numbers from 4 to 6... It gives me numbers like 8, 7, 9 etc...

## 4 Answers

###### Dmitry Polyakov

4,989 PointsTo get a numbers range starting and ending with some certain numbers that you want you need to use Math.floor(Math.random() * (max - min)) + min

max - is not included

For example:

Math.floor(Math.random() * (11 - 5)) + 5

You'll get numbers from 5 to 10 (11 won't be generated)

###### Dmitry Polyakov

4,989 PointsIt should work. I just checked it. It generates numbers from 4 till 9

###### Tomasz Grodzki

8,130 PointsWell... it still gives me numbers from 4 to 9. Im using exactly this code: var number = Math.floor ( Math.random() * 6 ) + 4; document.write ( number );

And I know the solution. I know that if I'll write: var number = Math.floor ( Math.random() * ( 6 - 4 + 1 ) ) + 4; document.write ( number ); then I'll get numbers from 4 to 6... But I don't understand why this first solution doesn't work well.

###### Dmitry Polyakov

4,989 PointsWhat result do you want to get?

###### Tomasz Grodzki

8,130 PointsIf code Math.floor ( Math.random() * 6 ) + 1 gives me number from 1 to 6... then why code Math.floor ( Math.random() * 6 ) + 4 doesnt give me a number from 4 to 6?

## Tomasz Grodzki

8,130 Points## Tomasz Grodzki

8,130 PointsNow I understand this formula. Math.floor(Math.random() * (b)) + a; Where "a" is the lowest number, and "b" is how many numbers program takes into consideration after "a". I simply thought that a is the lowest number and b is the highest number...