How many pens would it take to make a line that goes around the entire earth?

Ok, if there are approx 63360 inches in a mile, and the pen is 5.5 inches long, you would need 11,520 pens to stretch one mile. The circumference of the earth is 24,901 miles around, so 11,520 pens x 24,901 is 286,859,520 pens. Might want to check my work, as math is not my forte.

I can barely keep a pen without losing it for a month, how am I supposed to keep track of one for seven years?

Maybe you’ll take better care of it knowing that it’s not quite as disposable as regular pens?

Is the pen good for the English environment?

I’m… not really sure what you mean. It’s a pen, so you don’t have to worry about emissions or waste products regardless of whether or not you’re in England.