Probability is mathematical possibility of occurance of specific event
it denote as P(n). French mathematician chevalier de more a famous french gambler and amateur mathematician put forth a problem in grambling to mathematician . pascal who in turn discussed with fermat  about this problem and  the result of which was foundation of probability. theory of probability is developed by bernoulli,demoivere,fisher and others.
mathematical representation of probability is P(n)=P(E)/P(S)
P(E)= total no. of event and P(S)= total no. of sample
note this : 0<=P(n)<=1
find probability for 6 if dice is throwns onces?
p(E)=1 ie. only one 6 no. face in dice p(S)=6  ie. there is 6 faces in dice
thrown once means :
probability (n)=1/6