$\sum_{r=0}^{10} {}^{40-r} C_5$ is equal to

If $\frac{1}{n+1} {}^{n}C_{n} + \frac{1}{n} {}^{n}C_{n-1} + \dots + \frac{1}{2} {}^{n}C_{1} + {}^{n}C_{0} = \frac{1023}{10}$,then $n$ is equal to

The sum of the series $\frac{1}{1 \times 2} {}^{25}C_{0} + \frac{1}{2 \times 3} {}^{25}C_{1} + \frac{1}{3 \times 4} {}^{25}C_{2} + \ldots + \frac{1}{26 \times 27} {}^{25}C_{25}$ is

The sum of the last eight coefficients in the expansion of $(1 + x)^{15}$ is

$C_0 - C_1 + C_2 - C_3 + \dots + (-1)^n C_n$ is equal to

If $1^2 \cdot ^{20}C_1 + 2^2 \cdot ^{20}C_2 + 3^2 \cdot ^{20}C_3 + \dots + 20^2 \cdot ^{20}C_{20} = A(2^\beta)$,then the ordered pair $(A, \beta)$ is equal to