
theorem Th1162:
Sum digits(1750,10) = 13
proof
  thus Sum digits(1750,10) = Sum <%0,5,7%>+Sum <%1%> by Th1161,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%7%> + Sum <%1%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%7%> + Sum <%1%> by AFINSQ_2:54
  .= (0 + 5 + 7) + Sum <%1%> by AFINSQ_2:53
  .= 12 + 1 by AFINSQ_2:53
  .= 13;
end;
