The standard form for a complex number is a + bi, where i is the imaginary unit, . You do complex arithmetic (addition, subtraction, multiplication, division, and exponentiation) the same way as you do real number arithmetic. The imaginary unit, i, is located above the 0 key. Accordingly, press SHIFT i to enter i. The screen at right shows the familiar equation i2 = -1 obtained in the RUN-MAT screen.
Complex number arithmetic may be done from the RUN-MAT screen or from the CAS screen. The RUN-MAT screen provides answers in decimal form; whereas, the CAS screen gives exact answers. To access a screen, press MENU, then press 1 for the RUN-MAT screen or press 9 for the CAS screen. For example, we display (6 – 3i)/(4 + 5i) from the RUN-MAT screen (below, left) and from the CAS screen (below, right).