here is what I came up with...
I use a blank card, which is a container that has the sprite fonts for the numbers required (this automatically picks them when a card is picked). Without a separate card image for every question and answer, the game is a lot smaller in size.
swipe from the right to reveal answers, next question...
when you swipe from the left, it goes back to the last question (it doesn't go back to an answer).
after testing for a bit, the swiping gets a little tiring... might want to thing about a tap to reveal the answer on the current card, and then a swipe for the next card.
if you wanted to go up to 12x tables, you would have to shrink the font. I tried making the font proportionally spaced so that more characters could be displayed, but I thought it is batter to keep digits in fixed columns to help reinforce that the columns matter.
the Symbol sprite has animations for division, addition and subtraction - so it wouldn't be hard add extra modes from the menu layout...
https://www.rieperts.com/games/forum/FlashCards.capx