What is the sum of X+XX+XXX+XXXX?
Last Updated: 21.06.2025 07:44

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)
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
and for binary would be
What is the sum of X+XX+XXX+XXXX?
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
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
11010X
It’s a matter of interpretation.
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