For a given finite $A.P.$,$a=1, l=10$ and $n=10$. Then,$S_{10} = ........$

The students of a school decided to beautify the school on the Annual Day by fixing colourful flags on the straight passage of the school. They have $27$ flags to be fixed at intervals of every $2 \,m$. The flags are stored at the position of the middle-most flag. Ruchi was given the responsibility of placing the flags. Ruchi kept her books where the flags were stored. She could carry only one flag at a time. How much total distance did she cover in completing this job and returning back to collect her books? What is the maximum distance she travelled carrying a flag? (in $m$)

$A$ plastic toy consists of $14$ circular discs of different radii. The radius of the smallest disc is $1\, cm$, the radius of the next bigger disc is $2\, cm$, and so on, such that the radius of the biggest disc is $14\, cm$. Find the sum of the circumferences of all the discs in $cm$.

Find the sum: $(-5) + (-8) + (-11) + \dots + (-230)$.

Find the sum of two-digit natural numbers divisible by $6$.

For a given $A.P.$,$a=1$ and $d=2$. Then,$S_{10} = \dots$