What is the sum of X+XX+XXX+XXXX?
15.06.2025 02:24

It’s a matter of interpretation.
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
What is the sum of X+XX+XXX+XXXX?
11010X
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
Have you ever had a scary dream about a loved one or friend soon after their death?
and for binary would be
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
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)