How do I convert a number from sign and magnitude to twos complement?

Question

Got this class for college which ill never need again, how can I convert a number from (ex 1100) to twos complement and reversed? Any online calculator that can do this? I understand what twos complement is and what sign and magnitude is, just dont know how to convert them and how to add twos complement numbers

Answer 1

With two's complement it is trivially easy to negate a number: invert the bits and add one.

Take your sign/magnitude number and separate the fields. If the sign is positive, you're done. If the sign is negative, negate the magnitude as above.