Two students have to be chosen as monitors in a class of 36. in how many ways can this be done?

Total no of students in class = 36
No of students chosen as monitors = 2
There is no other condition, hence we can directly apply combination concept of choosing 2 students out of 36 = 36_ C_{2}
                                                                  =  \frac{36!}{2! * 34!}
                                                                  =  \frac{36 * 35 * 34!}{2* 1*34!}
                                                                  = 18*35
                                                                  = 630

Ans: 630