npub1vjduyt0yg752njzued79m8ulc7h8ulqh0z68wqy43fsld07g0ersjsrlky (npub1vjd…rlky) 0000 = 0
0001 = 1
0010 = 2
0100 = 4
1000 = 8
If you can just remember that doubling-ish sequence, you can add the bit values together and just remember that 9 counts to A and then up to F.