Since there are 26 black cards (1/2 of 52) and 2 black twos (one for each suite, and there are 2 black/red suites), we can use the same logic to get that there are 2 black eights. 2+2=4, and since there are 52 cards, you have a 4/52 or 1/13 (we get this because 4 goes into 52 13 times) chance of getting a black 8 or 2.