What is the sum of X+XX+XXX+XXXX?
10.06.2025 07:42

Given the use of upper case, I personally would initially assume Roman numerals*, so the answer would be C (100 in present-day decimal notation)
It’s a matter of interpretation.
11010X
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
as would be assuming that these are representations of conventional numbers, in which case the answer for number bases of five or more would be
1234X
Simone Biles calls Riley Gaines 'sick' over criticism of transgender athletes - NBC News
What is the sum of X+XX+XXX+XXXX?
and for binary would be
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
Devin Harjes, "Boardwalk Empire" and "Manifest" actor, dies at 41 - CBS News