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

Read also:

• When did you realize that your childhood was not normal?
• Chemists find a surprisingly simple way to remove microplastics from tap water - Earth.com
• 3 keys to success every Citadel intern learns their first week on the job - Business Insider
• The Universe's Most Powerful Cosmic Rays May Finally Be Explained - ScienceAlert
• I Can't Wait for Apple's F1 Movie. Its Haptic iPhone Trailer Has Me Even More Excited - CNET
• What's it like to have an IQ of 140 to 170? Do people notice you're different?
• Practice Report (6/9): Notes from the sideline - New York Giants
• Who are the actual "science deniers": people who wait until vaccines are proven effective, or people who believe that there are more than two genders?
• Harvey Weinstein Accuser Kaja Sokola: ‘The Devastating Part Was Not the Trial Itself — It Was the Betrayal of My Sister’ - Variety
• Why would my nipples hurt when I touch them?