Correct Answer: 221

The number 10⁵⁰ is a 1 followed by 50 zeros.

The number 10²⁵ is a 1 followed by 25 zeros.

On adding , we have

1000000… upto 24zeros 100000…. upto 25 zeros

When you subtract 123 from this number,

The 25 zeros that follow it are transformed.

The first 25 – 3 = 22 zeros all become 9s.

The last three digits become 1000 – 123 = 877

So number will be

1000 …upto 24 zeros 999……. upto 22 times 877

Now sum of all digits :

1 (the first digit) + 0 (from the 24 zeros)+ 0 (from the 25 zeros )+ (22 × 9) (from the 22 nines)+ (8 + 7 + 7) (from the last three digits) = 1 + 0 + 0 + 198 + 1 = 221