Probability is written as a fraction.
On the top (numerator) of the fraction, we place the number of options we are looking for.
On the bottom (denominator) of the fraction, we place the total number of possible combinations.
Look at these number cards.
What is the probability of selecting a number which is either greater than 8 or even?
There are 8 options that "we are looking for" (these are 2, 4, 6 and 8 and 9, 10, 11 and 12)
There are 12 "possible combinations".
The probability is 8/12 which reduces to 2/3