SOLUTION
Let us start with
a. To convert

To do this, we keep multipllying by 2 and keeping track of the whole number part. I will demonstrate this using the equation tab
So 0.6640625 ten to binary =

So to hexadecimal, 10 means A. So this becomes

(b) 27.625 means 27 + 0.625
So we will convert both the whole number part and the decimal part to base 2 and base 16, then we combine to get the answer

Now the decimal part

Therefore

To hexadecimal we will do the same, but 10 becomes A, 11 becomes B, 12 becomes C.


Therefore

That is 1B.A to base 16