# Multiplying and dividing real and complex numbers

1. Dec 30, 2015

### Einstein's Cat

• Member warned to do some basic research before asking questions like this one
Is it possible to divide and multiply complex numbers and real numbers and if so, how does one do that? If not, why so? Cheers for your help!

2. Dec 30, 2015

### Samy_A

3. Dec 30, 2015

### mathman

Multiplication: $(a+ib)(c+id)=ac-bd+i(ad+bc)$
Division: $\frac{a+ib}{c+id}=\frac{(a+ib)(c-id)}{(c+id)(c-id)}=\frac{ac+bd+i(bc-ad)}{c^2+d^2}$

4. Jan 2, 2016

### HallsofIvy

If you know what "complex numbers" are then you should have seen how to do arithmetic with them.