#C, 70 bytes
i,s;t(n){for(i=n;i;)for(n=i--;n;n=(n-n%10)/10)s+=n%10;printf("%d",s);}
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user56344
#C, 70 bytes
i,s;t(n){for(i=n;i;)for(n=i--;n;n=(n-n%10)/10)s+=n%10;printf("%d",s);}