1.
`A5_16 = 10.16^1 + 5.16^0 = 165_10`
165 ÷ 2 = 82, R = 1
82 ÷ 2 = 41, R = 0
41 ÷ 2 = 20, R = 1
20 ÷ 2 = 10, R = 0
10 ÷ 2 = 5, R = 0
5 ÷ 2 = 2, R = 1
2 ÷ 2 = 1, R = 0
1 ÷ 2 = 0, R = 1
`=> 165_10 = 10100101_2`
`=> A5_16 = 10100101_2`
2.
`10100101_2 = 1.2^7 + 0.2^6 + 1.2^ 5 + 0.2^4 + 0.2^3 + 1.2^2 + 0.2^1 + 1.2^0 = 165_10`
165 ÷ 16 = 10, R = 5
10 ÷ 16 = 0, R = 10 = A
`=> 165_10 = A5_16`
`=> 10100101_2 = A5_16`