0 z
1 a
2 b
3 c
4 d
5 e
6 f
7 g
8 h
9 i

example code : 7290008909860 -> gbiz3 hizihfz ->
gbiz3 hizi hufuz
with repeating codes can be omited ->
hizi hufuz

7290017386447 ->
z2 agc hufd dug  emp it up