fx991MS digital display but fx991ES is natural text book display.
To calculate complex numbers using the Casio fx-991MS, switch the calculator to complex mode by pressing the 'MODE' button until you select "Complex." Then, input the real and imaginary parts in the form "a + bi" using the 'i' button for the imaginary unit. You can perform operations like addition, subtraction, multiplication, and division directly by entering the complex numbers and using the standard arithmetic operators. Finally, press '=' to compute the result.
To do matrix multiplication in calculator Casio fx-991MS follow the steps below:- 1] Enter in the matrix mod:- press MODE 3 times then press 2. 2] To enter the matrix:- press SHIFT and then 4. press 1 to select Dim. to enter the matrix. Suppose u hv to multiply the matri A with matrix B then seletect A by pressing 1 chose dimension for matrix A let m=2 so press 2 then '=' again let n=2 so press 2 then '=' Now, enter the values in matrix MatA11, MatA12, MatA21,MatA22 every time enter the value and then ' =' to enter another values.. remember values get stored in the sequence of row mean 11,21,21,22 now u feel all the values of Matrix A now to enter value of matrix B press SHIFT and again 4. seect Dim by pressing 1. this time chose Mat B and follow the steps same as u use to feel values in matrix A. after entering the values. u stored matrix A and B. 3]Now multiply Matrix A and Matrix B:- press again Shift then 4 and this time select option Mat by pressing 3 to multiply matrix A and matrix B press 1(select Mat A) then press Multiply operator(*/cross). again press Shift then 4 then press 3 and nw selec/press 2(select Mat B) then press '=' 4] you will get the another matrix Ans But the values are in the sequence of row to see next vaues in that matrix press '>' side of REPLAY button.