ABC26GN0391 · Number System
Subject: General Aptitude · Chapter: Number System · Exam: · Marks: · Difficulty:
When $100^{25}-25$ is written in decimal notation, the sum of its digits is
Answer
Explanation
$$\begin{aligned} 100^{25}-25 & =\left(10^{2}\right)^{25}-25=10^{50}-25 \\ & =1 \underbrace{1000 \ldots . .00}_{50 \text { zeros }}-25=\underbrace{9999 \ldots \ldots . .9975}_{48 \text { times }} \end{aligned}$$ ∴ Sum of digits $=(48 \times 9)+7+5=432+7+5=444$.
Explanation as extracted from the printed page; notation may be imperfect.
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