Is the '0' side of d10 10 or 0?
Depends.
If you are rolling 1d10, then the 0 is 10.
If you are rolling 1d100 using two d10s, then the 0 is 0... unless both dice come up 0, then the 0s are 100.
Where in this card game do they ask for a 1d100 roll?
They don't; the original reply is imparting some 'general' dice rolling knowledge to someone who seems not to know.
@subzero - in this game, the '0' side of a d10 counts as ten (never zero).
thanks everyone!