We deal 1 card at a time , When you find a match between
2 cards,You click on both cards and they are removed.
And the rest of the cards are rearranged to the left and down
A match - when 2 cards have same number
The 2 cards have to touch each other-\
On the left, right, top, bottom or diagonal
Another way is to deal all cards and then click matching pairs
(More challenging)