Master multiplication facts and divisibility rules while having fun playing card games with this unique deck of 171 cards. In all four games players form factor sets. Because 80=8x10, the numbers 80, 8, and 10 form a factor set. Factor sets can have more than three numbers. For example, the set 42, 3, 2 and 7 is also a factor set. Prime wild cards are used for prime numbers only
