What is the sum of X+XX+XXX+XXXX?
13.06.2025 14:49

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
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 sum of X+XX+XXX+XXXX?
1234X
Japan’s oldest “human” fossils aren’t human at all, says new study - Glass Almanac
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
and for binary would be
Bitcoin update: From 80 bytes to 4MB – How BTC’s brain can get bigger - AMBCrypto