Bunuel wrote:

Official Solution:

What is the sum of digits in decimal notation of number \(10^{20} - 16\) ?

A. 158

B. 162

C. 165

D. 174

E. 183

\(10^{20}\) has 21 digits: 1 followed by 20 zeros;

\(10^{20}-16\) has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of \(10^{20}-16\) equals to \(18*9+8+4=174\).

Answer: D

Just one comment or perhaps it is my ignorance but I got confused by the text

in decimal notation They could had just written What is the sum of digits of number XXXXXXXXXXX?