Comment by Yopolo

It learned a concept of a heuristic which made it smart enough for the learning reward.

Might be an architecture issue or a parameter size issue that it didn't learn to do math like a caculator.

But look at your own math skills: How many numbers / how big of numbers can you keep in your head? How far is this heuristic away from how much a human learned until you start using pen and paper or a caculator?