Caluclate e the easy way, by adding the reciprocals of i factorial if i starts at 1. -> 1 1 1 1 1 1 1 1 ... - + - + - + - + - + - + - + - ... 1! 2! 3! 4! 5! 6! 7! 8! ... (fraction bar, not minus sign) or, sum of 1/(n!) as it goes until infinity (start at n=1)