List of top Mathematics Questions on Combinatorics asked in IISER

दो पूर्णांक r व l लीजए जिनके लिए r $\ge$ l $\ge$ 3 है। ऐसे कितने फलन f : {1, 2, . . . r} $\rightarrow$ {1, 2, . . . r} हैं जिनके लिए f(1), f(2), . . . , f(l) सर्वथा अलग-अलग हैं?

Let $r, l$ be two integers such that $r \ge l \ge 3$. What is the total number of functions \[ f : \{1, 2, \dots, r\} \to \{1, 2, \dots, r\} \] such that $f(1), f(2), \dots, f(l)$ are all distinct?

How many three digit numbers divisible by 5 are there in which no digits are repeated?

What is the value of $^{23}C_0 + {}^{23}C_2 + {}^{23}C_4 + \dots + {}^{23}C_{22}$ ?