How to solve

This is. It stackoverflow.

You know, there's this thing, this semi-holy Grail.
It's called stackoverflow and they know all kinds of stuff.
Scenario 1:
You get your working answer.
Scenario 2:
You get a false answer.
Scenario 3 (likely):
You get screwed over for asking.

Good night

It's simple math come fucking on. Are you 10?

@c3r38r170 that ain't simple math.

@Ranchu The notions of reminders and digits do are basic.

@c3r38r170 depends on what one defines as basic.

@Ranchu Adittion is already less basic than the positional value of digits, so are we going to assume he can't add?

@c3r38r170 Dunno, personally I've never seen any kind of task like this.

@Ranchu There, I've just solved it for positives, it's dead simple. It took me 20' with my phone in a JS interpreter I built, could've been 10, or less.