29-28-27-26-25-24-23-22-21-20
= 28-27-26-25-24-23-22-21-20
= 27-26-25-24-23-22-21-20
= 26-25-24-23-22-21-20
= 25-24-23-22-21-20
= 24-23-22-21-20
= 23-22-21-20
= 22-21-20
= 21-20
= 2 - 1
= 1
= 512 - 256 - 128 - 64 - 32 - 16 - 8 - 4 - 2 - 1
= 1
29-28-27-26-25-24-23-22-21-20 = 28-27-26-25-24-23-22-21-20
=27-26-25-24-23-22-21-20
= .................
= 21 - 20
=1