
theorem Th114:
Sum digits(91,10) = 10
proof
  thus Sum digits(91,10) = Sum <%1%>+Sum <%9%> by Th113,AFINSQ_2:55
  .= 1 + Sum <%9%> by AFINSQ_2:53
  .= 1+9 by AFINSQ_2:53
  .= 10;
end;
