How can I tell a negative binary number from a positive one? More specifically, what exactly is the difference?

For example, the binary number 1110 converted to a decimal number results in either 14 (positive) or -2 (negative). So which one would I write as the correct answer? Or are both values correct?

2 answers

(this is plagiarized) Adding a “1” to the front of it if the binary number is negative and a “0” if it is positive. However, using this sign-magnitude method can result in the possibility of two different bit patterns having the same binary value. For example, +0 and -0 would be 0000 and 1000 respectively as a signed 4-bit binary number.
in signed binary, both 0000 and 1000 are just 0
in ones-complement, 1000 = -7 since 0111 = 7
in twos-complement, 1000 = -8 since 0111 +1 = 1000 (or it may be treated as an error)