4.125
s = 0
bin= 100.001 = 1.00001 x 2^2
exp = 2, +bias = 2+127 = 129 = 10000001
0 10000001 00001000000000000000000

1 01111110 01100000000000000000000
s = 1
biased exp = 01111100
exp = 01111100-bias = 124-bias = 124-127 = -3
sig = .011 = 0.375
num = - (1 + 0.375) x 2^-3 = 1.375 / 8 = 0.171875