What number of permutation of the letters in the word smart?

For the first letter, you can have any of 5 choices. Then for the next, you can have any of four. Then for the next, three and so on. Thus the number of permutations can be calculated by 5x4x3x2x1. Doing this gives 120.

Therefore the number of permutations of the letters in the Word smart is 120.