
theorem Th1158:
Sum digits(1675,10) = 19
proof
  thus Sum digits(1675,10) = Sum <%5,7,6%>+Sum <%1%> by Th1157,AFINSQ_2:55
  .= Sum <%5,7%> + Sum <%6%> + Sum <%1%> by AFINSQ_2:55
  .= (5 + 7) + Sum <%6%> + Sum <%1%> by AFINSQ_2:54
  .= (5 + 7 + 6) + Sum <%1%> by AFINSQ_2:53
  .= 18 + 1 by AFINSQ_2:53
  .= 19;
end;
