Hi
My number length is +447832225144 (0-12)(or 13 if counted from 1)

I declared variable num var byte[12] because it can take my number from num[0]="+" to num[12]="4"

I also declared sum var byte[21] because :
sum[0]="A" and so on upto sum[7]="="
and further
sum[8]="+"
sum[9]="4"
sum[10]="4"
sum[11]="7"
sum[12]="8"
sum[13]="3"
sum[14]="2"
sum[15]="2"
sum[16]="2"
sum[17]="5"
sum[18]="1"
sum[19]="4"
sum[20]="4"
sum[21]=13

and to fill sum[8] to sum[20] we need loop 13 times (sum[8] included), and so c=0 to 12

Also while serout it needs to transmit whole sum[0] to sum[21] so c=0 to 21.

Do you still feel this is the wrong way? Thanks