Question 19
What are the last 2 digits of the sum
$$1+11+111+\cdots+\underbrace{111\ldots111}_{50\text{ digits}}?$$
$$1+11+111+\cdots+\underbrace{111\ldots111}_{50\text{ digits}}?$$
SASMO 2014 Primary 3 (Grade 3) Contest Question 19
SASMO · SASMO 2014 Primary 3 (Grade 3) Contest