### বাক্সবন্দী বল

##### Score: 1 Point

You have $20$ boxes in front of you. $1$st box has $2$ balls, $2$nd box has $3$ balls, $3$rd box has $4$ balls and so on. Then last box has $21$ balls inside it. In how many ways can you chose $2$ balls from a single box?

Combinatorics

#### Statistics

Tried 235

Solved 121

First Solve @azizulnafis