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3. Moving the point

Here is what it looks like as an actual value in an 8 bit register. In the mantissa there is one bit for the integer part and three bits for the fractional part. As there is a 1 in the leftmost digit, it is a negative number.

Just like scientific notation, to get this binary number back into its full form, the exponent is indicating where the binary point needs to go to. As the exponent is +2, shift the point two to the right. like this

If we place it in a binary table, its value looks like this :

The value of this number is

           -4 + 0 + 0 + 1/2
         = -3 1/2 or -3.5 

If this was stored in an 8 bit register it would be 1111 1001 where extra ones to the left pad it out to 8 bits as it is a negative number. If the number was positive, the extra bits would be padded out with zeroes.