Currency progression

Unit name	Number of Zeroes
K (Thousand)	000 (3)
M (Million)	000,000 (6)
B (Billion)	000,000,000 (9)
T (Trillion)	000,000,000,000 (12)
aa	15
ab	18
ac	21
ad	24
ae	27
af	30
ag	33
ah	36
ai	39
aj	42
ak	45
al	48
am	51
an	54
ao	57
ap	60
aq	63
ar	66
as	69
at	72
au	75
av	78
aw	81
ax	84
ay	87
az	90
ba	93
bb	96
bc	99
and so on...