(a) Canversion of (25)10:
25 = 12 x 2 + 1
12 = 6 x 2 = 0
6 = 3 x 2 + 0
3 = 1 x 2 + 1
1 = 0 x 2 + 1
(25)10 = (11001)2
(b) Conversion of fraction (0.8125)10
0.8125 x 2 = 1.6250
0.6250 x 2 = 1.2500
0.2500 x 2 = 0.5000
0.5000 x 2 = 1.0000
(0.8125)10 = (0.1101)2
Adding (a) and (b), we get,
(25.8125)10 = (11001.1101)2.