The score for clearing a stack is LevelMultiplier × (StackScore + ComboScore + ClearScore) where
LevelMultiplier is the level number in Classic mode, and level number + 9 in Quick mode,
StackScore is 1 point for the first card in the stack, 2 points for the second, 3 points for the third, ...,
ComboScore is 10 × Combo Number where Combo Number > 1, and
ClearScore is 100 points (for clearing all the cards in the play area).