Question 178
Calculate the sum of digits of the number
$$
1 + 11 + 111 + \cdots + \underbrace{111\dots111}_{\text{2023 1's}}.
$$
$$
1 + 11 + 111 + \cdots + \underbrace{111\dots111}_{\text{2023 1's}}.
$$
MathNet 2023-part-05 — 191 problems (EN–VI) Question 178
Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)