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# Negative Numbers

How do we account for users inputting one or two negative numbers?

parseInt() will work just fine with negative numbers.

Typing `parseInt(-5)` into the console will return -5.

The formula used to generate a random number will also work just fine with negative numbers.

`Math.random()` returns a number between 0 and 1 (not including 1).

Multiplying that by `(topNumber - bottomNumber + 1)` will give a number between 0 and the difference between `topNumber` and `bottomNumber + 1`, not including `bottomNumber`. So if our top and bottom numbers are 10 and 1 respectively, the random number will come out between 0 and 9.9999999...

Adding the `bottomNumber` will raise or lower the entire range so the lowest possible value will be `bottomNumber`.

So looking at the entire example where `bottomNumber = -5` and `topNumber = 7`:

• Math.floor(Math.random() * (topNumber - bottomNumber + 1) + bottomNumber)
• = Math.floor(Math.random() * (7 - (-5) + 1) + (-5))
• = Math.floor(Math.random() * (13) + (-5))
• = Math.floor([0 ≤ n < 13]) + (-5)) //Range doesn't include 13
• = Math.floor([0-5 ≤ n < 13-5])
• = Math.floor([-5 ≤ n < 8])
• = [-5 ≤ n ≤ 7] //Everything over 7 gets rounded down