Can i calculate calculus using fx-991ms

If you want to get an answer like 1/2X for d/dx(X^2), you will have to purchase a CAS calculator like Casio's Algebra FX-2 or Classpad. TI series calculators also have CAS.
However, you can calculate the numerical values of derivatives and integrals only.
To calculate the value of a proper integral:

1. Press the 'ON' key;
2. Press the Integral key ;
3. Enter your expression (example X^2+X-3 etc);
4. Press the 'comma' key after your expression;
5. Input the first limit after comma, input comma again after first limit;
6. Close brackets;
7. Press the equals key, display may return after a while with the answer.

for eg to calculate ∫xdx from 0 to 2, input as follows:

∫dx(X,0,2)

To calculate derivative at a point:

1. Press Shift and then the integration key.
2. Enter your function;
3. Input comma;
4. input the point at which you want to evaluate the derivative;
5. Close bracket and press enter.

Example, to calculate d/dx X^2 at 3 input:

SHIFT+∫dx key X^2,3)

Display looks like this: d/dx(X^2,3).

yes