What is the sum of X+XX+XXX+XXXX?
12.06.2025 01:03

It’s a matter of interpretation.
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
and for binary would be
Robinhood Traders Playing S&P Index-Guessing Game Get Schooled - Bloomberg
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
*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?
11010X
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)
1234X
If books could kill: The poison legacy lurking in libraries - BBC