Assuming Two's complement convert 10010110 to decimal.
To start off with as it is two's compliment (from the first bit being 1) we have to flip all the bits to get 01101001, then we must add 1 to get 01101010. Then we simply convert this to decimal using normal binary to decimal conversion while remembering that as we had to convert it it is a negative. This adds up to 106 so therefore -106.
CW