Multiset can contain duplicate elements, therefor for each position (total 4 positions) we have 6 choices.
Therefore total number should be 6*6*6*6 = 6^{4}

The number of ways possible to form injective function from set A to set B where |A| = 3 and |B| = 5, such that pth element of set A cannot match with pth element of set B are _________. can someone explain this question to me