Figure 2 Exponential form addition and multiplication

A fixed-point number can be represented as:
N + f*2-d     integer (N) + fraction (f*2-d)
This is represented in an integer by left-shifting by d bits,

which is the same as multiplying by 2d:
2d*(N + f*2-d)
=N*2d + f

(N*2d + f) + (M*2d + g)
= (N + M)*2d + f + g

(N*2d + f)*(M*2d + g)
=2d(N + f*2-d)*2d(M + g*2-d)
=2d(A)*2d(B)
=22d(A*B)
=2d[2d(A*B)]