In case of inputting square roots, press the square root button and activate it. To insert fractions, insert it converting into decimals. For example, \(\frac{3}{4}\) is to be inputted as \(0.75\). But the output will be in decimals. Again, for working with more irrational numbers like \(2+\sqrt3\), you must input it in decimal form using full-stop \((.)\) as the decimal point.

Complex numbers are usually in the form of \(a+ib\), where \(a\) is the real part and \(b\) is the imaginary part.
As such, two complex numbers \((a+ib)\) and \((c+id)\) would be multiplied.

Theory [Multiply Complex Numbers]

Two complex numbers \((a+ib)\) and \((c+id)\) when multiplied with each other results into:
$$(a+ib)(c+id)=(ac-bd)+i(ad+bc)$$
According to Euler's theorem, any complex number can be written into exponential form, which helps us to write the imaginary numbers in the form of:
$$a+ib=r_1e^{i\theta_1}$$
$$c+id=r_2e^{i\theta_2}$$
where \(r\) is the magnitude of the complex number (which has been indexed) and \theta is the polar angle the line joining the pole and the number creates with the real axis. Mathematically, they can be formulated as:
$$r_1=\sqrt{a^2+b^2}$$
$$\theta_1=\tan^{-1}\left(\frac{b}{a}\right)$$
$$r_2=\sqrt{c^2+d^2}$$
$$\theta_2=\tan^{-1}\left(\frac{d}{c}\right)$$

Multiplying the complex numbers results in:
$$(a+ib)(c+id)=r_1e^{i\theta_1}\cdot r_2e^{i\theta_2}=r_1r_2e^{i(\theta_1+\theta_2)}$$
Therefore, the magnitudes get multiplied upon multiplication of the numbers and the angles get added. There is another approach to this:
$$(a+ib)(c+id)=(ac-bd)+i(ad+bc)$$