How come you subtract the min from the max instead of adding 1 to the min first? I thought addition came before subtraction.
Math.floor(Math.random() * (max - min + 1)) + min
Also why does this equation work?
Thanks
Hello there,
Think through this:
2 + 3 - 1 === 3 - 1 + 2 === 2 - 1 + 3…
The equation you have above works like this:
Math.random() // Returns a number between 0 and 1
max - min // Returns the range
Math.floor() // Rounds the number passed in it down to the nearest whole number
So, 1 is added to the range because the number is rounded down, and you do not want to exclude a potential case where the result is equal to max.
min is added to the whole result, as, supposedly, you want a random number from min to max inclusive.
I hope that is clear enough.
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Ok thank you, I just dont get how 2 + 3 - 1 == 3 -1 + 2
2 + 3 - 1 == 4
3 - 1 + 2 == 0
If I am using PEMDAS, where addition comes before subtraction. Maybe I forgot something from math class but Im confused about that.
Well, I am used to BODMAS, where operation precedence (+ || - && * || /) occurs based on position, when reading left-to-right.
You can test it by typing it in the browser console…
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Oh ok, so PEMDAS does not work in coding??
PEMDAS:
Parentheses
Exponents
Multiplication AND Division
Addition AND Subtraction.
Multiplication/Division or Addition/Subtraction get parsed from left to right.
2 + 3 - 1 would be 2 + 3 which is 5, then 5 - 1 which is 4.
3 - 1 + 2 would be 3 - 1 which is 2, then 2 + 2 which is 4.
The way you are reading the second statement would be 3 - (1 + 2).
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oh ok thank you so much!
To be honest, I am not familiar with enough paradigms to be able to definitively say. As far as JS, Python, MATLAB go. BODMAS is the order of operations.
I believe BODMAS and PEMDAS are the same rules under different names.
Instead of “Parentheses, exponents” it’s “Brackets, order”. But the operations are all the same.