Find the number of permutations of the letters in the word SMART?

Thanks Trincent but you need to include some working or how can people learn from you ?

$${\mathtt{5}}{!} = {\mathtt{120}}$$

five choices for the first letter

4 choices for the 2nd

3 for the third

2 for the forth

1 fo the last one

5*4*3*2*1 = 5!

120