
theorem Th1136:
Sum digits(1275,10) = 15
proof
  thus Sum digits(1275,10) = Sum <%5,7,2%>+Sum <%1%> by Th1135,AFINSQ_2:55
  .= Sum <%5,7%> + Sum <%2%> + Sum <%1%> by AFINSQ_2:55
  .= (5 + 7) + Sum <%2%> + Sum <%1%> by AFINSQ_2:54
  .= (5 + 7 + 2) + Sum <%1%> by AFINSQ_2:53
  .= 14 + 1 by AFINSQ_2:53
  .= 15;
end;
