Your request is confusing - you can’t use signs, but yet you need to multiply numbers? Unless you dive into a level for bitwise shifting, I can’t see how you can achieve this.
So, I’ll go out on a limb, and assume you want the scenario that if variable var1 = 1 and var2 = 5, then var3 = 15. Please correct me if I misunderstand, and clarify your query.
I see two ways of doing this - the first, and simplest, is :
Alternatively, and a tad more complicated, you can take advantage of GDevelops weakly typed variables:
You can access the variable _result as a number variable:
Variable(_result)
[edit] Note, the second way is a bit easier if there are more digits in the number.