What number do you get deriving with going against the cross, yet with respect to the cross,
Then removing the with and using some imagination with the product?
Hint 1:
In this puzzle the crosses aren't the same.
Hint 2:
Prefixes are nice. You'll have to use them twice, at least thrice.
Hint 3:
When you cross the cross, be sure to beg mercy for it.
Final Hint:
The answer takes only one finger.