2.83

A.

n = 0.yyyyy...

n << k = y.yyyyy... = Y + n

n << k - n = Y

n = Y/(2^k - 1)

B.

(a).

y = 101, Y = 5, k = 3

n = 5/7

(b).

y = 0110, Y = 6, k = 4

n = 2/5

(c).

y = 010011, Y = 19, k = 6

n = 19/63