#combinatorics #thesumrule #stheproductrule #sumrule #productrule #permutations #ksample #factorial #permutation #permutationsindiscretemath #discretemath #discretemathematics #kinzabilal #educationworld #educationworldbykinzabilal #mth202 #mth202lec30 #mth202lecture30 #mth202lecture30bykinzabilal #mth202lec30bykinzabilal #mth202shortlectures #mth202shortlecture30 #mth202shortlec