What is the sum of X+XX+XXX+XXXX?
Last Updated: 24.06.2025 11:06

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)
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
What is the sum of X+XX+XXX+XXXX?
Administration to phase out NIH support of HIV clinical guidelines - The Washington Post
It’s a matter of interpretation.
11010X
1234X
Nuclear rocket engine for Moon and Mars - European Space Agency
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
and for binary would be
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
What is the future of AI and which are the best ones in 2025?