One word: Practice. I know you hear that majestic word everywhere, but it's true. If you want to get good at anything, practice.
"How do you draw so good?" Practice.
"How do you sing so well?" Practice.
"How do you play that game so nicely?" Practice.
Practice this, practice that.
1 million is 1 x 10^6
1 billion is 1 x 10^9
1 trillion is 1 x 10^12
So 12 trillion miles is 12 x 10^12 which converts to 1.2 x 10^1 x 10^12 = 1.2 x 10^13