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

Read also:

• Can you provide some examples of music with a free form structure?
• How much gold is there in the world? - Live Science
• Why would my ex block me after I blocked him?
• Why are people calling the Biden/Harris administration a disaster for the US economy?
• How do you think Trump's tariff threats are affecting Europe?
• Fans don't appear to be snatching up tickets to the Club World Cup - KING5.com
• Is there a type of function where every point has exactly one tangent line passing through it? If yes, what is this type of function called?
• Why do heterosexual men like anal sex with women? I think it's because they secretly want to have anal sex with a man? What do you think?
• Forget drones, Amazon has new robots that could replace humans - TheStreet
• Orioles Designate Emmanuel Rivera For Assignment, Option Heston Kjerstad - MLB Trade Rumors