I am going through the exercises of this old C programming book, that

doesn't have the answer in the back. Which is good.

However I am not understanding a particular question.

It says:

Write a program that estimates the value of the mathematical constant e by using the formula:

e = 1 + 1/1! + 1/2! + 1/3! + ...

I understand that 1!, 2!, 3! are the factorial of those numbers. But what

throw me off is how far should I go computing. Notice that is + ....

And if it is a constant how come it can be change?.

Anyone mind to show me some light on the matter?. I'm quite sure I can resolve the equation only if I knew what is being ask of me.