cmi-entrance 2019 QA4

cmi-entrance · India · ugmath 4 marks Arithmetic Sequences and Series Telescoping or Non-Standard Summation Involving an AP

The sum $$S = 1 + 111 + 11111 + \cdots + \underbrace{11\cdots1}_{2k+1}$$ is equal to . . . . . . .

The sum
$$S = 1 + 111 + 11111 + \cdots + \underbrace{11\cdots1}_{2k+1}$$
is equal to . . . . . . .