How many trees would it take to make 4000 rolls of toilet paper?

About 384 trees. This is how many trees are used to make the toilet paper rolls that one American uses within his or her lifetime. Here is the math:

"It takes 48 full grown trees to make roughly 500 rolls of toilet paper. So using that number it takes about 1/10th of an adult grown paper tree to produce 10 rolls of toilet paper. Every American in the United States, roughly 300+ million, uses at the very least 49 rolls of toilet paper a year. That is 5 trees a person." (from http://www.trap17.com/index.php/cut-down-trees-but-grow-faster_t55053.html)