Hello,

I have a project which is performing addition, multiplication and subtraction on a file of equations. Adding or subtracting a big number of equations and substituting a value of x in the result works correctly, I mean it's in the range of double format. But, multiplying 10 equations and substituting x = 1 in the result gives a number in millions, if x = 5, the value is(-1.#IND)and I don't know what does it mean. So, I was looking to use long double so that It may solve the problem, but when I code the following segment, the output is 0.0000;

So, I'm facing two problems, the first how can I do my project works for large values of X, or large number of equations, what format should I use? The second is, if long double is a solution, how can I use it?Code:long double num = 50; printf("%Lf", num);