When 100²⁵ - 25 is written in decimal notation, the sum of its digits is :

Solution (By Examveda Team)

100²⁵ - 25
= (10²)²⁵ - 25
= 10⁵⁰ - 25
$$ = \underbrace {\,1000\,.....00\,}_{50\,{\text{zeros}}} - 25$$     $$ = \underbrace {\,9999\,.....\,9975\,}_{48\,{\text{times}}}$$
∴ Sum of digits
= (48 × 9) + 7 + 5
= 432 + 7 + 5
= 444