Let 10 Bags $B_1, B_2, \ldots, B_{10}$ which contains $21,22, \ldots, 30$ different articles respectively. Then the total number of ways to bring out 10 articles from a Bag is

The number of 3-digit numbers we of the form $x y z$ with $x< y, z< y$ and $x \neq 0$ is

Suppose $A$ is denoted the set of all numbers between 1 and 700 which are divisible by 3 and let $B$ is denoted the set of all numbers between 1 and 300 which are divisible by 7 . If $C=\{(a, b) \mid a \in A, b \in B, a \neq b$ and $a+b=$ even number $\}$, then order of C is

If ${ }^9 P_5+5 \cdot{ }^9 P_4={ }^{10} P_r$, then the value of '$r$' is