You specified that your number is in the additional code. For further conversion, you need to get a direct number code. Therefore, let\'s perform the conversion from additional code to direct code.
to do this, first perform the conversion from the additional code to the reverse by subtracting 1 bit, then get the direct code by inverting all the bits except the signed one.
| || || || |
|-||1|| -1 bit|
let\'s translate to decimal like this:
1∙24+0∙23+1∙22+0∙21+1∙20+1∙2-1+0∙2-2 = 1∙16+0∙8+1∙4+0∙2+1∙1+1∙0.5+0∙0.25 = 16+0+4+0+1+0.5+0 = 21.510
got It: 10101.102 =21.510