What is the sum of X+XX+XXX+XXXX?

Read also:

• Are vampires real?
• Is crossdressing being a transvestite?
• Why do many men like women's breasts?
• Why can't we send flat Earthers to space and show them the shape of Earth?
• Why do men choose to marry a plain Jane woman over a pretty woman?
• ˗ˋˏ ♡ ˎˊ˗ NEW WOMAN - analysis ˗ˋˏ ♡ ˎˊ˗
• What is your most intimate experience with your best friend?
• What is the sum of X+XX+XXX+XXXX?
• To a flat Earther, what's wrong with the idea that gravity is simply a force inherent to space which operates only in one dimension? Why do they go further and try to deny gravity rather than just saying it's different than physicists claim?
• China Blasts Laser 80,000 Miles to the Moon in Broad Daylight – A First in Space History! - Indian Defence Review