The number of permutations of n objects is 

n ! = 1 × 2 × 3 × ⋯ × (n1) × n = 

1 × 2 × 3 × 4 × 5 × 6 × 7 = 5040 


The number of kpermutations of n objects is 

P(n, k) = = n × (n  1) × (n  2) × ⋯ × (n  k + 1) = 




The number of combinations of k objects chosen from n objects is 



