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

Read also:

• Valerie Mahaffey, actress in "Desperate Housewives" and "Northern Exposure," dies at 71 - CBS News
• Mysterious 'runner' dinosaur a sign there are more Jurassic secrets to unlock beneath western US - Live Science
• To those people in the world who have access to universal healthcare, what experiences could you share with Americans in order for us to understand how it affects your life (positively or negatively)?
• TSA shares travel warning for Costco members - TheStreet
• Scientists Calculate That the Entire Big Bang Must Have Taken Place Inside a Black Hole - futurism.com
• Exclusive | Kimberly-Clark Nears Roughly $3.5 Billion Sale of International Tissue Business - WSJ
• What exactly is digital marketing?
• Brazilian Gamers Infuriated by Sudden PS5 Price Hikes - Push Square
• Fasting Every Other Day May Be More Effective Than Daily Dieting, Research Finds - SciTechDaily
• Scientists Create Living Building Material That Stores Carbon Like a Tree - Indian Defence Review