Permutation & Combination


There are few letters, namely “GIIILK”.

  1. How many different ways the words can be arranged in a row?
  2. How many ways of arrangement that all three letters of “I” are together?


  1. 20
  2. 6

Permutation Formula

This formula calculates the number of permutations of n things taken r at a time

Combination Formula

This formula calculates the number of combinations of n things taken r at a time

Number of permutations of n things when there are n1, n2, …, nk repeated items.


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