Custom Expression Can't divide by the same value

Hey Everyone !

Here is my first question :slight_smile: I’m using metabase since few weeks now and really love it.
But I’m stuck with a custom expression and can’t find how to make it works !

What I want to do : Find the % of return users

How do we calcul it : Number of users who bought at least 2 times on our app Divide by total number of buyers.

What I do in MetaBase : I use the custom expression in my table where 1 row is 1 purchase with the user email. So I use two expression in my custome expression :
Count : For the total number of buyers
Distinct (email) : For the number of unique buyers

Actual numbers are :
Count is equal to 5539
Disting (email) to 4144

So the good answer should be : (5559-4144)/ 5539 = 1395 / 5539 = 25,19%

But when I do :
(Count - Distinct(Email)) / Distinct(Email)
I get 0% …

Whereas when I do : (replace the param Distinct(email) in the division by its value)
(Count - Distinct(Email)) / 5539
I get the good number 25,19%

Thanks a lot for any help :slight_smile: :heart: