+868 I have $3$ different mathematics textbooks, $2$ different psychology textbooks, and $2$ different chemistry textbooks. In how many ways can I place the $7$ textbooks on a bookshelf, in a row?
+37147 7 P 7 = 7! = 5040 ways
or
7 choices for first book
6 choices for second book
5 choices for third book
.
.
.
1 choice for last book 7x6x5x4x3x2x1 - 7! = 5040 ways
